M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: Blip Bavarian on June 11, 2009, 02:54:35 PM
-
My car will not start. I think that the biggest clue is that the CEL doesnt illuminate at all. I checked all relays and fuses in the fuse box and along the fire wall. All relays and fuses passed the test except.....The main relay (DME relay) did not pass the test. I applied power to 85 and 86, and then checked 30 and 87 with my multimeter. when i applied 12v of power to it, it did not click like all the other relays, also, the multimeter showed no continuity between 30 and 87.
I thought great. just get a new realy and voila.... Today i got my new main relay, and tested it. It did the exact same thing as the original "fried" relay. No click, and no continuity. I plugged it in, and still no CEL light. anyone know why the continuity test doesnt work on the main relay???
Here are my other symptoms
- No CEL ( cant do stomp test) My CEL used to work fine
- No buzzing from ICV
- No buzzing from fuel pump.
I have done a complete hose swap, and have cleaned out my sensors with contact cleaner.
I have been searching for other possibitlities of what the issue could be, and am left with 3 questions.
1 I have read that the ECU/DME may not be getting power. However, I do not know how to check this with my multimeter. Can someone please explain how this is done, or post a link.
2 Also i have read that it could be a bad connection at the fusible link. Once again i do not know how to check this.
3 Third i have read alot of people having issues with their CPS. I dont think that this is the case, b/c i dont think that that would knock out my CEL light... not sure though. Once again, I am not sure as to the proper pprocedure for checking this with my multimeter, and need help
Im sure there are other possibilities for the failure that i am unaware of. If you guys can help wuide me on how to thest the DME, CPS, and fusable link; That would be fantastic.
-
I'd think fusible link. I don't know why it'd cook, but it's not too hard to check it out. I've only done this on a 325is, so YMMV:
Pull up the carpeting in the trunk, look on the right by the wheel well. You'll see a plastic conduit held in with 2 or 3 plastic nuts covering the positive wires heading to the front. Get that conduit off and look for the small positive wire.
You'll see it has some heat-shrink tubing on it, cut some of that away (maybe 4-5 inches) until you find a large bulge in the middle of the wire. That will have more heat shrink tubing...cut that away too.
You'll be able to inspect the fusible link there, it's a little square PCB with one fat trace on it. It's all riveted together, so you'll have to re-wire if it's bad. I just used a small nut & bolt and lots of electrical tape to fix my old 325is, but the car was so rusty I didn't care about it much. I think it's rated 80amp, so plan ahead accordingly.
-
I've always tested the DME by looking for the check engine light. If that's not on, you know it's either burned out or the DME isn't powering it up. You are right...even if the CPS is bad, the check engine light will still work and the DME will still fire plugs. It just won't pump fuel.
The CPS can be tested by pulling the lower connector on the wiring plenum toward the front of the engine:
(http://i729.photobucket.com/albums/ww299/desktopdave/th_IMG_1472.jpg) (http://s729.photobucket.com/albums/ww299/desktopdave/?action=view¤t=IMG_1472.jpg)
It's in the middle of the picture...click to see a larger version.:cool:
Switch your handy meter to ohms, test pins 1 & 2. Should be 680ohms, give or take 10%. At least that's what I've heard...just tested mine at 580. I had to clean the sensor once...it was encrusted with oily residue from my leaky front main seal (replacement is planned) and I suspect the dirt was mostly metallic...no magnetic signal means no fuel pump signal from the DME.
-
Okay, so this leaves me to believe that it is probably the DME, since im getting no CEL. Do you know how i can test it with the multimeter to see if it is getting power? What setting should my multimeter be on and where do i place the probes?
i would rather check that the DME is getting power before i start pulling the shrink wrap off the fusable link...
It is curious that all this happened as when i did the hose swap...
as always, thanks DD for the advice. I really appreciate it.:)
-
I found this advice for a 325, but ours should be the same:
http://forums.bimmerforums.com/forum/archive/index.php/t-1206661.html
For the DME to run power must be present on DME connector pin 27 (Start input), 18 (Unswitched power) and pin 37 (main relay output). The Start input is supplied from the ignition switch and when present causes the DME to engage the main relay and power up the DME. A problem with any of those or the main relay would result in the engine drop outs, a flash of the CEL, and no codes.
I can't think of another way to test the wire without taking it apart, unless we can find it and isolate it for a continuity test.
-
any advice on how to locate pin 27, 18, and 35?
then i assume i do some sort of an ohm test...?
-
Nope, you'd just test to see 12vdc on the DME pins.
I think you could use a LONG set of leads to do a continuity test on that positive wire. I'm not 100% sure this will work, but it's pretty painless. Here's pics of both sides, click to enlarge:
(http://i729.photobucket.com/albums/ww299/desktopdave/th_IMG_1474.jpg) (http://s729.photobucket.com/albums/ww299/desktopdave/?action=view¤t=IMG_1474.jpg)
See the small black wire? Unbolt that. Attach a wire as a testing lead from that to your meter and only to your meter...make sure it doesn't touch anything else because it'll weld itself to anything metal if the fusible link is good...:eek: Go to the trunk.
(http://i729.photobucket.com/albums/ww299/desktopdave/th_IMG_1475.jpg) (http://s729.photobucket.com/albums/ww299/desktopdave/?action=view¤t=IMG_1475.jpg)
See that battery terminal? Put the other meter lead on that and test for continuity or voltage. I've also circled the troublesome fusible link. It's easy to get to.
-
DD, if i followed your instructions correctly, there is no continuity.
here is what i did. i attached a jumper from the positive terminal of the battery to one probe of the multimeter. Then i disconected the small wire that you show in your picture. I connected a jumper from that wire to the other probe of my multimeter. with that connected i showed no continuity.
The key was in the off position for the test....
ive got an idea...
i also have a secondary 12v source. if i used a jumper and connected the positive side of the 12v source to the small wire in your pic, would that power up the ecu??
-
Pull the insulation and fix the burned out fusible link. Like I said, I used a small nut & bolt I had laying around and taped it all up well. You don't want a short there.
If you wanted to do a professional job, you can probably get that part at the dealer. Alternatively, go to an auto parts shop and pick up an inline fuse holder. I'd guess that it's a 10 or 15 amp link. It's wide but very thin. I also heard someone joined it with a trail of solder.
-
i just opened up the fusible link. I pulled all the shrink wrap off. It looks like metal at both ends with a rubbbery center section. when i tested for continuity from one metal end of the fusible link to the other (across the rubbery gap), there was no continuity. is my line of thinking correct? there should have been continuity right?
i guess you are right. this is the problem.
i tried to test it by attaching a small jumper with small clips at each end to eaither end of the fusible link. Therefore connecting it? then turn my key to half position.... the CEL did not light up. I went back to the trunk to check on it, and there was a little bit of smoke in the trunk. The rubber on the little jumper was melting. i unhooked it and it sparked, and the jumper was really hot with melting rubber.....
needless to say, the CEL did not come on.
-
Well, you know half the problem...the fusible link should have a little metal strip going across that center section. Now you just have to find out where the short is. There is no way that the DME is pulling that much power.
I'd guess that there's some insulation rubbed off that wire going through the frame somewhere, since it didn't blow a fuse in the box. You could test that for continuity to ground when it's off the battery...just test to any good ground on the car. If you get continuity, then you'll have to check that whole wire. It runs alongside the passenger side frame, between the seat and the door frame. The seats come out easily, four big bolts.
-
Well, you know half the problem...the fusible link should have a little metal strip going across that center section. Now you just have to find out where the short is. There is no way that the DME is pulling that much power.
I'd guess that there's some insulation rubbed off that wire going through the frame somewhere, since it didn't blow a fuse in the box. You could test that for continuity to ground when it's off the battery...just test to any good ground on the car. If you get continuity, then you'll have to check that whole wire. It runs alongside the passenger side frame, between the seat and the door frame. The seats come out easily, four big bolts.
when i had the small jumper bridging the link, i turned the key half position. i didnt get a CEL. Then i tried to crank the car. I think that when i tried to crank it is when the jumper got hot and began to melt the rubber.
I was just using small guage hook up cable from radio shack, which im sure was not sufficient.
i do have the strip of metal on the link. It is broken in half. When i did the hose swap, i didnt disconect the battery. Maybe that is when the link blew....
also if there is a short, would it have to be in that main wire? Or is it possible that it could be anywhere. I have some exposed wires hanging out where my stereo used to be. My car is completely gutted, so it shouldnt be that hard to find an exposed piece in the main wire if there is one.... if i find an exposed piece what do i do? just wrap it in electrical tape?
-
It's hard to say where the short is. I'd suspect that there is a short in that wire from the battery to the DME. I'd say it's chafed in the rear seat area, where it runs through the seat back. Might also be chafed in the front of the car, coming through the firewall. I'm thinking that it just took a while for the vinyl to melt, while you were cranking the car it was long enough to get hot. Cheap metal has high resistance...that's why they use such high-grade copper and insulation for auto wires.
I'll bet you have no other blown fuses...but check to see if I'm right. If so, it has to be in the battery harness...there are no other unfused wires in the car. The stereo power wires run through the fusebox and the speaker wires use a 'floating' ground that goes directly to the speakers...so it can't be them.
If you do find torn insulation just fix the cause and wrap the wire in some electrical tape. It won't need a whole lot of insulation, one or two layers. It's just important that it's covered. Those positive wires can carry a lot of current...especially that big fat primary positive wire...make sure it's intact and happy.
IMHO it didn't burn out when you did the hose swap, unless you doused the DME.
-
I will check all of the fuses tomorrow, and then i will look for a chafe in the wire. hopefully i can get the issue resolved this weekend. My gf is gonna kill me if i spend any more time in the garage.
i didnt douse the dme at all during the hose swap. it just seems strange that the car would crank, and the stomp test showed a vacuum leak before the swap, and then when i put everything back , and it wouldnt crank. i guess it could be unrelated.
Thanks so much for all of your help Dave. I probably need some more advice on how to repair/replace/rig my fusible link....
here is a pic of an inline fuse holder. Is this what you are talking about using in place of the OEM fusible link??
(http://installcaraudiosystems.com/wp-content/gallery/images/fuse_fuseholder.jpg)
If so, what would that entail?
-
Yeah, I'd get something like that...with an assortment of fuses. I can't find good info about the rating of that fusible link, but I've seen 20amp, 30amp & even 80amp. If I had to guess, looking at how thick the smaller positive wire is, I'd start at 20 amps and work my way up.
I don't know what to tell you about the GF. I use the car as marriage therapy...I can keep myself from annoying my wife while I'm working on the car.:D
I'd also clean the wires with some flux & solder that sucker in with a setup like that one above. Or just use a nut & bolt with some electrical tape...idle it for a while and see if it melts. What's the worst that could happen?:rolleyes:
-
The inline fuseable link is rated at 50 amps
-
Wow, 50 amps to run that DME. Who knew? That's a max rating of 600 watts...my file servers don't need that much power!!
-
I'd also clean the wires with some flux & solder that sucker in with a setup like that one above. Or just use a nut & bolt with some electrical tape...idle it for a while and see if it melts. What's the worst that could happen?:rolleyes:
What are you talking about melting? The electric tape around the nut and bolt?? I have no idea what the worst that can happen is...:D
i've never soldered before. How easy is it? would it be worth it to buy a cheap radio shack soldering iron and do it myself???
is this the type of fusible link i need to get??
http://www.bmaparts.com/item.wws?sku=VWW004082&itempk=73400&mfr=CRP&weight=0.01 (http://www.bmaparts.com/item.wws?sku=VWW004082&itempk=73400&mfr=CRP&weight=0.01)
here is a 50 amp, but im not sure if this is what i need. Can someone confirm... Part # 1241-1706111
http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=12-41-1-706-111-BOE&catalog_description=Genuine%20BMW%20Part%3A%20FUSE%20%2A (http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=12-41-1-706-111-BOE&catalog_description=Genuine%20BMW%20Part%3A%20FUSE%20%2A)
I would think that i just need the strip, but this second product from pelican looks like more than just the strip in the picture...
-
You won't have to solder the wires right away...just strip & twist them temporarily to see if the car will start. It's just a good idea for a permanent repair. Loose wires, connectors and grounds will make you tear out your hair...if you work on old Japanese bikes, you'll understand the wisdom of this statement.
Get a cheap inline holder like this one:
http://www.tti-plus.com/8-Gauge-MAXI-Fuse-Holder-W-Weather-Cap-50-AMP-Fuse-p/tti-maxi-f8g-50.htm They're probably for sale at Advance Auto, Pep Boys, etc. Get some spare 50-amp fuses too.
Check the wire for shorts/shot insulation, etc. FIRST. Then go check for other blown fuses. Then start on replacing the link.
Pull the positive cable off the battery, cut the fusible link out, strip some wire, twist those leads together with the fuse holder, temporarily tape them up, reconnect the battery and try to start the car. Go back and check the wire to see if it's abnormally hot or the fuse is blown.
Soldering is pretty easy...there are lots of tutorials out there. It makes a really nice electrical contact, so you don't have to worry about high resistance in the wire melting or burning stuff. Flux is an acidic cleaner that provides a path for the solder to flow.
After you've fixed the problem, disconnect the battery again, pull the tape off, brush some flux on the exposed copper, heat the wire with the iron until you can melt solder into the copper, wrap it up with electric tape (or fabric tape, plastic split conduit, heat shrink), enjoy your now-running car. Double check the holder after a short test drive, carry spare fuses just in case.
I use the 15/25watt radio shack switched iron. Fine electronics need small irons. Those 50watt solder guns are a little overkill but they melt the solder quickly! Don't hold the wire for too long, copper transfers heat really well.
Finally, don't worry about getting it wrong. Just try. Sometimes you'll make expensive mistakes, but sometimes it'll work and you'll save a bunch of money. I was a kid trying to make a too-old car work with crap tools and no experience once too...old SAABs are far more difficult than old Bimmers!
-
so i went by Pep Boys on my lunch break and picked up an inline fuse holder. Rigged it up with some electric tape, and connected the battery. Pop! the fuse popped. So i inspected the main wire, didnt see anything exposed. My car is gutted, so it is pretty easy to inspect.
I then put another fuse in, and connected the battery. This fuse didnt break. so i got in the drivers seat, turned the key to half position, and no CEL. THen i went ahead and tried to crank the car. There was a pop sound from the engine bay, and all of the lights on the dash went out.
I went to the trunk and checked the fuse. It is still in tact. got back in the drivers seat, and turned the key to half position. Still no lights at all on dash, but the light in the trunk was on. I tried to start it and it did absolutely nothing.
I guess the next step is to check the fuses and relays, to see if they are okay buyt i had to get back to work.... Any ideas on what might have happened? Or what to do next...
ps. i dont know of any way to check the main relay.. the method i used on all other relays as described above doesnt work on the main relay.
-
Wow, 50 amps to run that DME. Who knew?
it fires more than just the DME. acording to the electrical troubleshooting manual it also runs the fuel pump, o2 sensor heater, fuel injectors, crank and cam position sensors, thottle position switch, idle speed actuator, and the evaporative purge valve among others.
-
That's a lot of problems for the car to have. You have some big short in the harness somewhere. You might also have a bad starter...something is drawing a huge amount of power to blow those fuses. I'd start checking every inch of that wire.
-
Disconnect the big wire at the starter and turn the key to start. If the fuse doesn't pop, you know where to start looking.
-
I'm still trying to figure out what would have happened to cause this. The hoses you deleted are all pretty much separate from the electrical system. I'm stumped...I can't even guess at what happened.
I'd go get the e30 electrical troubleshooting manual and start from scratch. The ETM has loads of great info...and it systematically breaks the car down into systems that you can eliminate gradually. I hate that I don't have an easy answer for you here...we found the symptom but not the root cause.
Anyway, fuses blowing like that are only from overloads, right? So you only have two possible causes. Either there is a short in a wire, or an electrical component is internally shorted. That manual is around here somewhere...
After checking for any shorts, the starter is a good place to begin...you could likely take it out for testing just to be sure it's good.
-
so, i have some new info. went through the and checked the small wire that runs from the battery positive terminal to the engine bay, and then to the main relay.
the short/problem occurs after the main relay. when i hook everything up with the main relay disconnected, the fuse doesnt blow. the second i plug the relay in, the fuse blows. the leads me to believe that the short or issue is between the main relay, and the DME/ECU.
i dont know of any way to check the ECU. Can i take the ecu to the dealer and have them check it somehow, or do i need to get a replacement and try that??
If the issue is the starter and not the ECU, wouldnt my CEL work? Also, I would think that the starter is okay since the car cranks, it just doesnt turn over. Is mine line of thinking correct??
-no fuel pump buzz
-no CEL
-no ICV buzz
-
Your line of thinking sounds correct, but that wire powers more than the DME. Might not be the DME...could be any of the other components. You already tested the main relay, so I'd assume it's OK. I'd guess the old relay had an over voltage kill it, then that blew the fusible link? So I'd go check out all this stuff tom d suggested next...
it fires more than just the DME. acording to the electrical troubleshooting manual it also runs the fuel pump, o2 sensor heater, fuel injectors, crank and cam position sensors, thottle position switch, idle speed actuator, and the evaporative purge valve among others.
I'm thinking I'd pull those connections except the DME, then short the main relay socket with an inline fused wire from 30 to 87. The car won't pump fuel without a signal from the CPS, but if the fuse is good, re-connect them one by one. You'll be able to find out where your trouble is that way.
I went out to look at that wiring harness going from the small positive wire...looks like it goes to a lot of places. The electrical troubleshooting manual is your friend...
-
i dont know how to test the main relay. I attempted to test it by applying 12v to it, and then checking continuity from 30 and 87. For some reason it doesnt work. The relay doesnt click or show continuity. I tried this on a brand new relay that had never been plugged in. It didnt click or show continuity.
can someone point me in the direction of the electrical troubleshooting manual. This is the first i heard of it. i did a search, and didnt get much..
so i now realize that that cable controls more than just the DME, but, i think i read somewhere on here that the only thing that would keep the CEL from lighting up is if the DME is not getting power. if the issue was not the DME, and was one of the other parts such as the fuel pump, wouldnt the CEL would work, and wouldnt i be able to perform the stomp test..
thanks for the help DD
-
http://www.m42club.com/forums/showthread.php?t=7748 That page points to the hosted page http://www.mediafire.com/?kyzmz0yedr0
Yeah, you're right...if you apply 12v to 85-86 you should have a click and continuity from 30-87. Some relays need large (>0.5amp) current to close, so small batteries won't work. Alternately, you can just jump 30-87 on the relay plug to remove the relay as a problem.
You're right about the CEL too. Unless the bulb is burned out, the light will come on every time the system initializes. In your case, I suspect the relay is burned out, or carrying too much current, and the DME never gets a chance to start. So no CEL.
It remains to be seen if we're really helping...but we're here for you.
-
thanks for the help DD,
i am going to try an eliminate the different options that the main relay connects to. To do this do i simply unplug all of the sensors that relate to the main relay (fuel pump, o2, ICV, etc..) then connect power to the battery. If the fuse blows, then it is definitely the DME. If it doesnt, then it is one of the other accessories that relates to the main fuse. Then i would plug a sensor back in one by one, and when the fuse blow, then that accessory is the problem?
Is the the correct way to disconect each of the accessories just to unplug the sensor that relates to it? Or is there another way that i disconnect them?
-
It's not that easy, but you have the right idea. You can eliminate the sensors systematically that way. It's not perfect because it won't allow for the wiring runs, but it'll let you narrow things down to one misbehaving component. That's how I'd go at it anyway.
So, like you said, find out everything that gets power from that wire and unplug those components. If the fuse blows it's either the DME or the wiring harness. If not, plug things in one at a time until you blow the fuse.
-
Sounds simple enough. But when you say plug them in one at a time do you mean reconnect the sensor, or is there another way to deprive power from each component?
Also, i have read a couple of places; and it was mentioned in one of your posts, that you can test the power to the DME. Something about checking for power at pin 27....
in a post on a different forum someone mentions jumping power to the ECU pin, and then the car will start. Dont know exactly what this means.
Where is the pin located? Do i have to remove the ECU to do this?
Sorry for the barage of questions. THanks for all the help. -Matt
-
Yeah...unplug whatever you find connected to that power line, then turn on the key. Reconnect each sensor/component one at a time while the ignition is on and wait for the fuse to pop.
The ECU pins are on its connector and harness above the glove compartment. I'll bet he's just using a probe to jump power to the DME or using an inline tap to jump it inside the engine compartment.
You have to be careful about that because the DME is pretty sensitive to +12v in the wrong places. That's an easy way to trash it IMHO. I'd focus on other sensors or a short in the wiring harness somewhere - I don't think the DME could possibly be pulling enough current to pop that fuse. Maybe I'm wrong...anyone else know better?
-
so i started by unplugging the fuel pump sensor at the pump, both Crank and cam sensors, the TPS, the MAF sensor, the ICV sensor, and completely removed the DME. I hooked up the battery cable and pop. the fuse blew...
-
Damn...that doesn't make it very easy, does it? Maybe start doing continuity tests on that positive wire? At least the wiring harness is easy to get to...
-
i have continuity all the way to the main realy. Therefore the short or issue must take place after the main relay.
I dont know how to do continuity tests from the main relay to any of the components that the main relay powers.
The fact that the fuse blew when the DME was unplugged completely leads me to believe that the prob is not the DME itself
-
I agree. I'd pull the small battery connector on the firewall, then start testing continuity to a good chassis ground. Unplug things until you don't have continuity; that should be your troublesome circuit. Since that harness is always 'hot' nothing should have continuity to ground.
I looked at that harness...you'll need a little luck and a lot of persistence...do you have the wiring diagram? That'd help a lot.
-
I printed out the troubleshooting manual that you gave me the link to, so i have that. Do you have pics or a description of the small battery connector on the firewall that you are talking about. Im not quite sure what to look for. there are 2 circular plugs between the fuse box and the "firewall relays" is it one of those? Thanks Dave.
I agree. I'd pull the small battery connector on the firewall, then start testing continuity to a good chassis ground. Unplug things until you don't have continuity; that should be your troublesome circuit. Since that harness is always 'hot' nothing should have continuity to ground.
I looked at that harness...you'll need a little luck and a lot of persistence...do you have the wiring diagram? That'd help a lot.
-
WOOT WOOT. hooray. i got my car started.. Thanks so much DD for all of your help and advice. I really appreciate it.
I was about to roll over and pay to have it towed to a shop. I decided to give it one last shot, and check every wire in the engine bay again... Turns out when i put the upper manifold back on after the hose swap, I pinched part of the "fuel injector wire", and it was shorting out on the manifold, thus blowing the fusible link, and in turn not allowing the DME to power up.
I now have a fault code because of the mangled wire but that is for a new thread. For now i am enjoying the small victory of getting it started.
Thanks again Dave for helping so much.:)