1997 850 NA Automatic not starting

[erikv11]

It's in the thread, just a bit obscured.
Turn key, no lights no camera no action.
Bypass ignition switch by applying 12V to the solenoid, joy.

[BlackThunder]

@Dj_v70 and everyone, thank you for the detailed info. My time to work on the car is so sporadic that I can't ever really know when I'm going to get 10 minutes free - being a relatively new Dad is superceding my Volvo time but that is ok

I re tested the 50E pin on the relay just to make sure I didn't screw it up before and no change (see video)


I probed the green wire while having my wife reluctantly turn the key to start the car (see video for readings)



So it looks like I need to do a PNP switch replacement?

Dustin

[dj_v70]

Dustin,

Your latest video for voltage on 50E is different than the original. Note in the original when key was turned you only have 140mV (wrong answer). The latest video shows 10.56V, that is essentially the right answer. I expected over 12V, but this is close enough for the moment (only because the wire doesn't go anywhere at the moment because relay is removed). So, this is a likely pass.

Next step is to get a wire and jumper 50E to 50F of your relay socket. This bypasses the relay like you asked for earlier. I didn't ignore your request earlier per se, I just didn't want to look it up unless required. Bypassing the relay on this specific car also bypasses the immobiliizer. So, if this jumper makes your car start when turning the key, it is either the relay or immobilizer that is your issue. If it isn't, you should verify that you hooked up correctly (and that I gave correct relay positions to you) by verifying 12V at the remote start connector in your fuse box. If remote start connector has 12V with jumper connected and key turned, it is time to start looking at PNP.

I am confused regarding your last video, so ignored it. Could you please explain the exact circumstances of this measurement. I am assuming you are measuring the green wire while the key is turned but the relay is still removed. You are effectively reading 0V, which is the expected case if the relay is removed or the circuit is still broken somewhere (which I assume is why we are still trying to troubleshoot it).

[brunocerous]

With the red wire hooked up like that, you are doing what turning the key is supposed to do - providing 12 V to where the green wire connects. Since your wire works but the key doesn't, then as dj_v70 said, something is wrong in the regular electrical path from the battery to the where the green wire connects.

According to dj_v70 (sorry, I didn't dig up the wiring diagrams and read them myself), the normal electrical path is:
(1) red post on battery, then through that little red wire on top to and on to the ...
(2) ignition switch
(3) alarm relay
(4) PNP
(5) where the green wire connects

So you see, actually, just pulling the relay was not the suggestion. Look at the path 1-2-3-4-5 above: when the alarm relay is out, the key will never start the car, because you have broken the electrical path at position 3.

The suggestion was to pull the relay, put the red voltmeter cable into pin 50, put the black to ground, then turn the key and see if the voltmeter reads 12 volts. You may want to read the post by dj_v70 about this again. If it reads 12 V, then the path is good up to position 3 and you will want to do a similar test for position 4, after the PNP.

Alternatively, you can test the alarm relay by reaching up where it goes and jumpering it, but I don't know which socket hole you need to jumper to the hole for pin 50; likely someone else does.

It is sounding like a PNP problem but to figure it out you need to test each segment.

Sorry to jump on this thread, but it has been helpful to follow the diagnostic procedure here. I just have a quick question: How do you test the PNP? I'm getting 12V at the relays but not at the green starter wire. Any help would be greatly appreciated.