Update on starting issues (see Pic)

[Flamin'Cow]

Ok, thanks to some help I have received from this and another forum I (think) I have narrowed down the problem of my intermittent starting.

Supposedly if the 'motronic' or 'starter' RELAY is on the way out, then that would explain why the car starts sometimes - but not others.

Would someone please explain to me WHAT the relay (arrowed) is for as when I remove it the car wont start (wont even turn over and no 'click' from the solenoid) - which is exactly the same symtoms as I am getting with my 'occasional' non-start. If this relay is on the way out - would that explain my starting issues?

Also, what is the little black wire with the greeny-yellow stripe that connects to THE TOP of the starter solenoid? it seems that the car starts, with/without this connected - is it important?

http://i31.photobucket.com/albums/c392/flamincow/fuse.jpg

Thanks for your help

Flamin'cow

[genphreak]

I don't know, but I'll guess-

relay is the starter motor relay, so removed you get no solenoid power and hence no starter motor cranking.

ie Switch in keybarrel powers a 30A Relay which in turn powers the 200A solenoid which powers the starter motor itself.

Relays cna be repalced or repaired- often dirty contacts, armatures that have lost their spring or dry joints are at fault.

I'll guess that Pin 14 on the engine connector directly powrs the solenoid
(black/yelllow wire)... but its a long shot!

Good luck, :) Nick

[Flamin'Cow]

Thanks for your help, re the relay - gonna have to go to the stealership and get a new one...

As for the wire, the car starts (when it starts) with OR without this wire connected!

[DaveVoorhis]

Also, what is the little black wire with the greeny-yellow stripe that connects to THE TOP of the starter solenoid? it seems that the car starts, with/without this connected - is it important?
As I recall (don't have wiring diagrams handy here at work) it's used to indicate to the ECU and other systems that the starter is powered.

BTW, if you need to spin the starter without engaging it, you can temporarily connect battery +ve to that connector.

[Ross]

I believe the wire is connected to the OBC.
Try switching the relay with the other one or just change it for a new one, they are cheap.

[myles]

Only autos have that relay. It is will prevent the starter solenoid from getting power if the car is not in Park or Neutral when starting.

Manual cars have a jumper or bypass plug there.

[RobPatt]

...tells you what the relay is for... maybe not how it works, but...

[Flamin'Cow]

Errr - My car IS a Manual, got a clutch, 5spd gear-box - the whole lot! (and no it isnt one of those fitted with a clutch 'switch' - which must be depressed in order to start).

Also, the diagram in the lid of the box only tells me what the fuses are for - not what the relays are for/do....

If this wire were not to be connected - would that perhaps cause an issue? - Its strange as the car still starts (sometimes) even with this wire detached!

[DaveVoorhis]

If this wire were not to be connected - would that perhaps cause an issue? - Its strange as the car still starts (sometimes) even with this wire detached!
No, listen: That wire does not power the starter. It is used to indicate to other systems that the starter is being powered. The starting system is pretty simple. If it's not the solenoid, then it's likely the ignition switch or a wiring problem. You need to isolate whether the starter is being powered when it fails to turn over, and whether anything else is being powered when it fails to turn over. Next time it fails, get out your voltmeter and start tracing, and if you need a wiring diagram ask me and I'll send you one.

[myles]

According to the wiring diagrams, and if your car is a manual, that is wiring diagram part number B900 Jump Plug. It sits in the circuit between the ignition switch and the starter solenoid.

Dave - On 1992 model cars(such as yours) a different relay sits in that position

[DaveVoorhis]

True. I was referring to a '90 535i wiring diagram, which I'm guessing is the same as the '89. I'll pull the '89 diagram off a CDROM if asked. By "solenoid" I was referring to the starter solenoid. Flamin'Cow needs to verify whether or not the starter solenoid & starter are getting B+ when the ignition switch is turned to "start," and trace backward from there. It's even possible the jumper is defective.

[myles]

The diagrams indicate that 08/90 or 09/90 was the date that these things got changed around.

I'm looking into a similar occasional starter problem and I'm thinking the same thing for my diagnosis as you suggest. Its just that it's so occasional that when it does happen I'm not in a position to diagnose.

[myles]

If this wire were not to be connected - would that perhaps cause an issue? - Its strange as the car still starts (sometimes) even with this wire detached!


I'm not sure what the wire is that you're referring to. But it "might" be to supplement the power supply to the gm, obc, ihkr and srs modules during starting. Not sure about this though, I'm still trying to understand the purpose of this curcuit fully.

[DaveVoorhis]

I had a similar problem in my '90 525i, especially in hot weather. B+ was definitely getting to the solenoid, which pretty much pinned it down to the solenoid itself. I didn't bother replacing it, because I found I could jar the unit into behaving by briefly running the starter by jumping battery +ve to the upper terminal on the solenoid. That spins the starter without engaging the flywheel, which was apparently enough to vibrate the solenoid into working the next time the key was turned. I'm sure it eventually would have failed completely, and I warned the new owner that he'd probably need a new solenoid.

[DaveVoorhis]

I'm not sure what the wire is that you're referring to. But it "might" be to supplement the power supply to the gm, obc, ihkr and srs modules during starting. Not sure about this though, I'm still trying to understand the purpose of this curcuit fully.
I believe he's referring to the lead on the top of the solenoid. The terminal to activate the solenoid is on the underside of the solenoid. It might be a supplemental supply -- I assumed it was to advise other systems that the starter was activated, but I didn't follow it further once I determined it wasn't involved in spinning the starter.

[myles]

I hadn't considered it being an idication to the other modules. That is quite valid, the ihkr would want to know to turn the A/C off, the GM should not operate the power windows etc. All the high power drain and load components should probably be off during starting. Good thought, I might do some testing over the weekend.

[Flamin'Cow]

Thanks Dave, A wiring diagram might be of assistance as I only have the crappy one that comes with the Haynes guide :-(

I am getting power to the injectors (as they 'hum') when I turn the key, but nothing to any of the connectors on the starter/solenoid - nothing - its a dead circuit (but not all the time).

Although this wire doesn't power the system, if it were to be disconnected for a period of time/starts, would that perhaps fool the OBC into thinking that there was a problem with the starter/solenoid and therefore not 'allow' the car to start? - Just thinking out loud here....

[Flamin'Cow]

Yeah, my first thought with the problem was that it was a starter/solenoid issue, but I have since replaced the solenoid and as the starter works perfectly (when it starts) its not that......

Another interesting point I thought I'd say is that yesterday (it was raining) so I had my windshield 'defog' going. When I tuned it off (after clearing the winbshield) it didnt switch off fully (could still hear the fan going). Now whenever I turn the key in the ignition to click '2' I can hear the fan come on! - The switch for the A/C is off, as is the switch for the de-fog, rear window de'fog and the blower is 'off'. I took the fuse out (fuse 19) and that stopped it, but when I put the fuse back in and turned the key again, they came on - really strong as first - then gradually died away until I was left with nothing but a high-pitched squeal.......any ideas?

[DaveVoorhis]

Thanks Dave, A wiring diagram might be of assistance as I only have the crappy one that comes with the Haynes guide :-(
When I get home from work in a couple of hours, I'll put all my E34 wiring diagrams on the Web. Once done, I'll announce their availability in a new thread.

[joshua43214]

If you have good reason to suspect a bad relay, just replace it. All relays fail at some point and they are cheap, so its easy to justify.

The small second wire on the starter is a feedback circuit to tell something that the starter is engaged. It can do anything from activate the cold start injector to tell the car to turn off the blower fan and all other accessories depending on the application.