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Intermittant no crank: Seeking location of the 4-pole connector, elect dist unit

deadken

Member
Joined
Mar 31, 2009
Location
Long Island, NY
I bought my 1992 745 from 15A a few years back. It suffers from an intermittent no crank, especially when temperatures are warmer. I can always jump the starter to get it to crank, so it never leaves me stranded. But, I'm getting tired of being ghetto on an otherwise decent car (never mind the hanging interior light, that is an acceptable level of ghetto at the moment).

The connection at the starter solenoid is fine. When I checked for voltage at the starter solenoid during a no crank condition, I find less than 8volts and the starter won't crank.

So, I looked up the wiring diagrams and found that the blue wire with the green tracer goes to the connector at the left strut tower. I opened the 8-pin connector (blue / green wire in one of the corner positions) and the connector is clean and tight (I'll have to bring my multi-meter back to NY on my next trip). So, I would like to check the connections at the "4-pole connector, electrical distribution unit". I'm not sure where that is, but that is what is described on the wiring diagram.

Can anyone steer me in the right direction?

Here is the wiring diagram I am referring to:
https://www.carknowledge.info/wp-co...lvo-940-wiring-diagram-speed-control-1991.jpg

The starter motor is #9 and on the right side of the diagram. The solenoid wire goes through connector C, then A, and then F. Like I said, I checked connector A. I am going back outside to look around the left wheel housing for connector C. I figured that I'd ask about where connector F would be located before I went back outside.

Thanks in advance for any helpful and / or humorous responses!
 
If the car still has it's original ignition switch, that could easily be the problem.

Wow! Knowing that a lot of parts were changed into this car from a later car, I was figuring that it was just a bad connection at one of the plugs in the wiring harness.

Is that a common problem? If so, I'm guessing that I'll need to get a new one and have it keyed to match the rest of the car.

Since I know that the engine, the A/C system, moon roof, fuel tank, instrument cluster, etc... are not original it wouldn't surprise me if it wasn't original. But, knowing that most things that aren't original were changed in order to be updated (squirter block, R-134a, glass moon roof, etc.) I doubt that the ignition switch was changed.

I'm trying to think back to when I stripped my 1992 940T, I don't remember the key cylinder being an easy thing to change out from the ignition switch. Do I have that wrong?
BTW: I loved working on the Mercedes Benz cars from a certain era. You'd turn the key to the on position, insert a paper clip into the hole that opened up, and you could remove the key cylinder by tugging on the key. So simple and nicely engineered! I'd think if the Volvo set up was similar, I would have remembered it.
 
There are 4 terminals on the end of the solenoid. The top large one goes to the battery. The lower large one is permanently connected to the starter motor. The small terminal near the engine should have 12V with the key switch in the ON position. The outside small terminal should also have 12V but will be grounded when the key is moved to the start position. You can also manually touch this terminal to ground and the starter should crank and start the engine.

If you just here a loud click then the solenoid is bad. If you here both the click and a loud clunk (starter gear engaging the flywheel) but no crank then the starter motor is bad.

If you hear nothing then check that the key switch is pulling the outside small terminal to ground.
 
Wow! Knowing that a lot of parts were changed into this car from a later car, I was figuring that it was just a bad connection at one of the plugs in the wiring harness.

Is that a common problem? If so, I'm guessing that I'll need to get a new one and have it keyed to match the rest of the car.

Since I know that the engine, the A/C system, moon roof, fuel tank, instrument cluster, etc... are not original it wouldn't surprise me if it wasn't original. But, knowing that most things that aren't original were changed in order to be updated (squirter block, R-134a, glass moon roof, etc.) I doubt that the ignition switch was changed.

I'm trying to think back to when I stripped my 1992 940T, I don't remember the key cylinder being an easy thing to change out from the ignition switch. Do I have that wrong?
BTW: I loved working on the Mercedes Benz cars from a certain era. You'd turn the key to the on position, insert a paper clip into the hole that opened up, and you could remove the key cylinder by tugging on the key. So simple and nicely engineered! I'd think if the Volvo set up was similar, I would have remembered it.


The switch itself. Not the lock cylinder. The switch is attached to the back end of the lock cylinder with two slotted screws. It is easiest to replace with the instrument cluster removed. You can sit in the driver?s seat and reach through the opening where the cluster normally resides and replace the switch. It?s about a 1/2 hour job this way. Yes, it is getting to be a very common issue as old as these cars are now.
 
Wow! Knowing that a lot of parts were changed into this car from a later car, I was figuring that it was just a bad connection at one of the plugs in the wiring harness.

Is that a common problem? If so, I'm guessing that I'll need to get a new one and have it keyed to match the rest of the car.

Since I know that the engine, the A/C system, moon roof, fuel tank, instrument cluster, etc... are not original it wouldn't surprise me if it wasn't original. But, knowing that most things that aren't original were changed in order to be updated (squirter block, R-134a, glass moon roof, etc.) I doubt that the ignition switch was changed.

I'm trying to think back to when I stripped my 1992 940T, I don't remember the key cylinder being an easy thing to change out from the ignition switch. Do I have that wrong?
BTW: I loved working on the Mercedes Benz cars from a certain era. You'd turn the key to the on position, insert a paper clip into the hole that opened up, and you could remove the key cylinder by tugging on the key. So simple and nicely engineered! I'd think if the Volvo set up was similar, I would have remembered it.

Volvo also has this setup providing the key turns the lock cylinder. But this issue is for a different chapter.
 
The switch itself. Not the lock cylinder. The switch is attached to the back end of the lock cylinder with two slotted screws. It is easiest to replace with the instrument cluster removed. You can sit in the driver?s seat and reach through the opening where the cluster normally resides and replace the switch. It?s about a 1/2 hour job this way. Yes, it is getting to be a very common issue as old as these cars are now.

Thank you again for your help. I'll give replacing the ignition switch a whirl.

I was referring to the ignition switch, but unaware that it was held in by two slotted screws. I remember working on MB ignition switches and playing with a lot of Saab ignition cylinders when I used to work at a European auto repair shop.

FWIW: Saab manual transmission cars had a lock out in which you couldn't remove the ignition key without the transmission being in reverse. Apparently, owners forgot to tell other people that when other people drove their Saab 900's. Well, probably forgot to tell them once... After getting a repair bill from us after someone forced the key out without the transmission in neutral probably made clear instructions move the forefront of owners minds. Relevant useless trivia: Saab 900's (and maybe even the 9000's) had the ignition cylinder in between the front seats behind the shifter.
 
@ jofrasier: Thank you for trying to help. I'm sorry to disagree, but my experience is very different from your description. The ignition cylinder sends 12V to the starter solenoid, not ground. Please refer to the wiring diagram I included in the original post. I also explained that I am getting less than 8V to the solenoid when the no crank problem is evident (again, it is an intermittent problem). When the problem is evident, I jump 12V from the battery terminal to solenoid in order to start the car, not ground. It isn't a bad starter nor it is a bad solenoid. It is a problem with less than 8V getting to the solenoid intermittently when the ignition is turned to the crank position.

@lummert: Thanks for the suggestion. The first time it happened I tried moving the shifter into neutral (and then shifting it around neutral with the key in the crank position. The neutral safety switch has been ruled out.

I'm wondering which Volvo's had a similar set up. But, like you said, it really isn't for this chapter. Please know that you have my curiosity peaked!
 
NSS

@lummert: Thanks for the suggestion. The first time it happened I tried moving the shifter into neutral (and then shifting it around neutral with the key in the crank position. The neutral safety switch has been ruled out.

If the safety switch is bad, it may not necessarily work in either position.

When mine was bad, it did not work in either position or by jiggling it.
 
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