No start, no power to solenoid but I have 12v on starter? - solved

**PrivateVariable** · 07-09-2018, 08:51 AM

This is a 1994 740iL I'm working on. I had an issue last year where the starter would only "click" when put into the start position. I ended up just swapping the starter, worked like a charm.
Then I started having the same issue again a year later. The vehicle would start after about fifty clicks of the key into the start position. This lasted for a while and I could get the car working.
Now, I can't get it to start at all, and I'm not getting that distinct "click" sound anymore. I'm getting power to the starter good, but the solenoid is not getting power.

Checked for 12v at starter.
Checked the fusable links from + on battery.
Checked the power at the ignition switch at the start position, getting 12v on yellow/black (that's the lead to the starter relay).
Checked the fusebox at the starter relay input, getting 12v from there, so there's a good connection to the ignition switch.
Checked the starter relay, it is clicking, I can hear it switching. I even tried swapping it out with a functioning relay to make sure.

I am not sure about the neutral safety switch. I have no idea how to test it. I have the shifter console out and I have access to it, I just don't know how to test it (couldn't find good instructions, everyone says to replace it).
I also don't know if power from the starter relay goes directly to the solenoid, and the neutral safety is just wired to the Motronic to disable ignition, or if the neutral safety completely disables turning over.

Thanks for any help you can offer! I'm assuming that the new starter helped because it was more sensitive to the low input to the solenoid, and over time it just got a weaker
and weaker signal, and that's why I'm not getting the solenoid to work anymore.

**whiskychaser** · 07-09-2018, 11:24 AM

Well, I think you are nearly there. The yellow/black line goes from the ignition switch to the starter and is just interrupted at the starter relay. The relay is activated by the gear lever switch which has to be in P or N. So if the relay is throwing, it does not sound like you have an issue with the gear lever circuit.

But what you don't say is if you have power coming back out of the relay at pin 87. From there it goes to a starter junction box which, according to the wiring diagram, lives on the top left hand side of the engine bay. Could be that you have a bad connection between the starter relay and the junction box or between that and the solenoid itself. Wiring diagrams are here:

http://www.wedophones.com/BMWManualsLead.htm

**e30luv318i** · 07-09-2018, 11:25 AM

Large gauge should be constant 12v, starter grounded through motor, black yellow should be 12v on key pos start. If you have 12v on black yellow at starter upon crank you have a bad starter, if you have nothing go to start relay located front fuse box I believe top left row from memory? Check for input on start at relay if you have that (sounds like you do since you have it at the ing switch) you can bridge the 2 wires (input+output) together to run the starter. This is how the manual e32 is run it will not harm the car. At the starter relay make sure you have all you grounds and powers if your good you have a bad relay. But for the time being bridging the 2 wires will adleast make you mobile.

**PrivateVariable** · 07-09-2018, 11:51 AM

Originally Posted by whiskychaser

Well, I think you are nearly there. The yellow/black line goes from the ignition switch to the starter and is just interrupted at the starter relay. The relay is activated by the gear lever switch which has to be in P or N. So if the relay is throwing, it does not sound like you have an issue with the gear lever circuit.

But what you don't say is if you have power coming back out of the relay at pin 87. From there it goes to a starter junction box which, according to the wiring diagram, lives on the top left hand side of the engine bay. Could be that you have a bad connection between the starter relay and the junction box or between that and the solenoid itself. Wiring diagrams are here:

http://www.wedophones.com/BMWManualsLead.htm

Wow, thanks so much for the help, that is some super useful information I was having a hard time getting. I'm going to be further diagnosing the issue later today or tomorrow. First time I've every troubleshooted a real life electronics issue, despite I have knowledge in the area. Glad to see there are still some people out there with plenty of E32 knowledge ready to help out.

Also, thanks to e30luv318i as well, I was wondering if I could just manually jump the relay to do a proper diagnosis on the relay, but I couldn't find a good pinout of the relay. I know the relay shows the diagram on the side of it with the switch activated by the neutral safety switch and all, both of your replies helped me understand this system to a greater level of detail. I will be back once I have the issue fixed!!!

**whiskychaser** · 07-09-2018, 12:20 PM

Something I forgot to mention. Make sure your engine ground is intact and sound. If it isn't, you can have all the +V in the world to the starter and solenoid and it still will not turn over

**PrivateVariable** · 07-09-2018, 02:47 PM

Originally Posted by whiskychaser

Something I forgot to mention. Make sure your engine ground is intact and sound. If it isn't, you can have all the +V in the world to the starter and solenoid and it still will not turn over

That's interesting you mention that. A while ago the CCM was throwing an error about the oil level sensor, and Shogun said it may actually be the engine ground strap. I wonder if that has since taken a turn for the worst.

But I think the real problem will end up just being the connection to the solenoid, as I'm not getting any +V to the solenoid at all.

**PrivateVariable** · 07-10-2018, 05:40 PM

At the power distribution box I have taken off the two sets of smaller wires that are held on by a nut. The lower right set of wires had some pretty decent oxidation, so I took a wire brush to them both. The other set of wires found in the center behind the right larger +V to battery (or alternator don't know which) where also taken apart and cleaned of oxidation. After cleaning both sets of wires I'm still getting no +V to the solenoid, so I'm assuming a continuity check is in order for both sets of wires. Like I said, I'm getting power to the starter relay, and it is clicking when the key is turned, so I'm assuming the problem lays here. Any suggestions?

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**PrivateVariable** · 07-10-2018, 06:10 PM

Just a quick update, I'm noticing extremely heavy green oxidation on one of these connectors, not on the connector it's self, rather where the wire is crimped to it.

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**whiskychaser** · 07-10-2018, 06:48 PM

That looks a lot like the starter junction box I mentioned above

Your black/yellow wires should run to that from the starter relay and away from it to the solenoid. (page 122 of your wiring diagrams). Entirely possible that the wire is corroded away under the crimp. Give the terminal a twist. If it falls off, you have your answer

**PrivateVariable** · 07-10-2018, 08:48 PM

I've got power from the black/yellow coming to the junction. Had to wrap up troubleshooting for today (just moved out and live 40 minutes from my BMWs :p). I'm gonna test continuity from the junction to the starter for the solenoid wire.

Any idea what the black/green wire is? That's the one that is badly corroded at the crimp that runs to the junction, and not to the starter. I'll check the diagrams as well, just asking in case I can't figure it out.

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**Avec** · 07-11-2018, 11:57 AM

If I recall, the green and black wire is hot when key is in run or start. It will be required to activate the starter relay

**PrivateVariable** · 07-11-2018, 12:32 PM

This wire is after the relay. It's at the junction right before it goes down to the starter.

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**whiskychaser** · 07-11-2018, 01:50 PM

Diagram shows black/green wire as live feed out from starter junction box to OBC,GM and IHKA.

Assuming that when you turn the key, you get live on the black/yellow wire arriving at the junction box, the only suspect left is the connection between there and the solenoid. Exactly as you said above

**PrivateVariable** · 07-11-2018, 05:40 PM

Connector on the starter came right off with almost no effort! This is the culprit! Should have checked that first...

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**whiskychaser** · 07-12-2018, 04:00 PM

Reward for patient and logical fault finding

**PrivateVariable** · 07-12-2018, 09:14 PM

Had to replace the starter, but it fired right up! Driving it with the bad connection and clicking the starter a million times to get it going every time wore the starter out

Thanks for all the help! My favorite car in the world

(other than my 850 of course!... Maybe...)

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