After convincing myself that the problem was the starter solenoid, I picked up a new starter/solenoid and installed it this afternoon. I was all proud of myself when it started without a problem when I was done.

Unfortunately it was short lived. I drove around for a while, had dinner at at a restaurant and when leaving, the car refused to start. after a few minutes, I removed the center console and exposed the neutral safety switch. I pressed on the neutral safety switch and the car started up. Must be the neutral safety switch.

When I got home, I stopped and restarted the car several times without issue. I decided to install the replacement neutral safety switch I had available.

Now I am back to not starting again.

I have the circuit diagram in a Haynes manual. I am going to try troubleshooting it tomorrow with my voltmeter

 

those haynes diagrams are more of guidelines, they aren't 100% accurate. wiring colors change.... in the wiring details, there's probably 3-4 different versions of the 740, from 1983 to 1992.

 

Since I don't have another Volvo to compare with how can I track it down?

On the starter, I am assuming the small wire is the wire coming from the neutral safety switch.
On the neutral safety switch the colors are pink, blue, blue/red and black, labeled 0, P, +, R respectively.

I have the console out so I can also inspect the ignition switch wiring as well if needed.

Appreciate any insight on how to troubleshoot this.

Take Care.

 

I had a similar problem with a brick a few years back, I ended up replacing the starter.

https://volvoforums.com/forum/volvo-...o-start-60529/

One thing I remember is that sometimes I also wouldn't get any clicking when turning the key, but the dash lights turned on.

 

How many miles are on the brick? Does the starter look cleaner than the surrounding area?

 

I found a diagram of the starting circuit that seems to match the color scheme on my 88 Volvo.

The blue/red indicated 12V as expected.

The interesting one is pink. If I am interpreting things correctly, when the key is turned this should have 12V and it does not.

I am in the process of removing the ignition switch so I can troubleshoot it.

 

the neutral safety switch (aka 'start inhibitor' on my wiring diagram) has 2 wires, pink and blue on my 1991 schematic. on the 4 pin connector thats just upstream from it the blue wire converts to blue-green. you can jumper the pink wire to the blue-green wire and bypass the neutral/park safety switch entirely.

the pink wire should be 'hot' when the ignition is turned to III or 'START', its off in run. this is the actual signal to the starter solenoid. it comes from pin 50 of the starter switch.

on your left fender, there should be a single wire connector hanging out with nothing hooked up to it, the connector shell is usually blue, and the wire is pink. this is also the 'starter' signal, used for servicing, and if you use a jumper wire to hook this up to the "+" terminal of the battery, and the starter/neutral switch is working, the starter should turn over (even if the engine is switched off). handy for compression tests and such. so if that works, odds are its your ignition switch thats bad.

 

I have similar problem with my 740, try this. If you jump the blue and pink wire, will the car start? If so the neutral safety switch is bad. (I had to pull the gear selector slightly out of park to get it to start). I cut the blue and pink wires, ran a new set of lead wires from them up to the dash and installed an N.O. spst switch from radio shack in a switch blank next to the dimmer switch. Push the button, turn the key, energize the starting system and go. Don't push the switch and the safety system works as designed. I don't have any pictures, but I think I found this solution on matthewsvolvos site.
Andrew

 

I have the ignition switch in my hand. You mentioned pin 50 goes to the starter inhibitor switch.

The drawings in my Haynes Manual are really bad. Can't read all of the text and certainly not the wire colors.

The 12V in to the switch comes in on which pin(s)?

When you turn the key to the start position, which pins get shorted so that 12V exists on pin 50?

 

Now I am making progress. The car had a remote start system installed about 20 years ago. The remote is long gone and the remote start hasn't been used in ages.

In this last bunch of troubleshooting, I had just left the remote start hang down on the left of the break peddle.

I noticed the wiring harness on the back of the remote start was loose. In the harness is plugged in well, the car starts. If it is disconnected the car won't start.

I would like to remove the remote starter but I need to make sure the wiring actually goes back to the way it was or I will be back to square one (probably further back than that).

 

power into the ignition switch is on 2 red wires to 2 pin 30's. these two red wires both come from the 'positive terminal', on my 1992 740 that 'positive terminal' is a small flat black plastic box with a bunch of red wires hanging down, attached to the firewall above the pedal assembly.

the whole starter circuit is...

pin 50 of the ignition key is a pink wire that goes to a splice, one pink wire from the splice is the service jumper under the hood, the other one goes to pin 4 of the connector near the shifter, where its pink to the actual starter inhibit switch, and blue coming back to pin 3 of that same connector to a blue-green wire to pin 1 of the big block bulkhead connector at the left A pillar to a blue-green wire to pin 5 of a 8 pin block connector near the left wheel well to another blue green wire to pin 50 of the starter solenoid.

a remote start switch probably also needs to be wired to the ignition, the blue-red wire from pin 15R of the ignition switch goes to the fuel injection system and ignition system via the man fuse panel behind the ashtray, there's also a red wire spliced off that blue-red wire which goes to a blue wire to pin 1 of the ignition coil

these colors are all from my 91 diagram, its possible your 89 varies some.

anyways, my guess is, a remote starter would need to tap the red always-on power, and tap the blu-red ignition/injection power, so it can connect hose together bypassing the key, then it would need to tap the pink starter wire.