Help - 88 volvo no crank

[740phil]

My 740 wont crank over

The green wire to starter is not hot with key turned

The starter runs if I run a jumper from battery to starter - green wire

I cleaned the switch on the ( auto) shifter , it’s making contact ok

Schematic shows a start inhibitor switch , is that the same switch? It might be referred to as a neutral park switch or similar I could not detect a hot wire there despite the position of shifter

I think I need to verify if pink is hot when key turned to crank , I’ve got a spare ignition switch if it’s bad since I took a whole car apart for spares

maybe I need to cut into the harness for access to check , I think it’s a pink wire - for cranking

Schematic shows a test point for cranking starter motor , is it on drivers side in engine bay near firewall , I wasn’t sure what it looks like or if I should feed it 12 V or what

A “starter relay” is mentioned but I’m unable to find such a relay and the diagrams of relay locations on Mathiew’s relay site don’t seem to show such a relay

Can anyone verify if there is a relay involved in the starter motor crank circuit ?

Does the wire from shifter switch run directly to starter motor To feed it hot when key is turned and shifter in park or neutral ?

i Think it’s likely a bad key switch, do I need to change the key and ignition complete assembly or can I just change the switch itself ?

I know there are a couple of bolts there that I’ll need to cut (screwdriver) slots in with a dremil to remove the key switch as an assembly

. any other tips or things to look for ?

I’ll try to verify if I have hot at key switch pink ( I think it’s the pink )

, if not I’m thinking it’s a bad key switch . Maybe I can spray in some cleaners ? Deoxit ? I’m thinking might be best to just swap key switches, if I can use the same key it’s nicer so it fits the doors.

I have too many Volvo keys to carry already because I’m addicted to them

Of course stuck and frustrated without my car but I think I’m basically on the right path , it’s just hard to follow the wires , physically

Thanks all !
Phil

[740phil]

Thought I’d add this :

When I turn key to “crank” it’s disabling some things like the interior light maybe headlights

So since the position does that it seemed like the switch must be working - tgat confused me

I’m thinking maybe Volvo wanted to turn some stuff off like maybe headlights during cranking , to save amps for cranking , so it might be an entirely different key switch contact that does that

[740phil]

I replaced the key switch by removing speedo and plugged in a known hood switch
and if I turn it to crank . still no cranking happening

I noticed that there is a relay clicking too it’s at the drivers side, left front row ( or drivers side corner and toward rear of car)

Hind says it’s “J” window winders/ electric fan.

If I push down in that relay gently with a finger with key on it clicks which is weird if I keep pressing it it keeps clicking - this seems to be indicating a socket issue for that relay

The fan which I “coincidentally ?” Just replaced , works fine , as do the window motors.

I’m going to pull the console and try to pull out the relay, it may be that this relay info on the location I have is wrong and it’s for some other reason
I’ll see if my fan and window motors can run with it pulled out and check that thise relay socket wires aren’t burned up, it might be for the seat heaters ?

I need figure out where the wire runs as it goes from the key to starter switch , I still can’t understand why my starter isn’t getting it’s hot from

I have a whole pretty intact wire harness that I pulled out when I stapled a car , so maybe I can trace things out physically from that snarl of wiring , maybe easier to follow tge Irving with an old harnesses detached from a car

I’m still so confused but can’t see anything wrong with the starter key switch or the neutral/ park safety switch ..

[volvolugnut]

When did this car last start and run? Do you have a manual with electrical schematic? Do you know Brick Board site may be better forum to 40 ask about 240 and 740 Volvos? The 740 is very similar to the 240.
volvolugnut

[740phil]

Thanks for that, I can probably condense the post and repost there
If no one is really able to help here

It started and ran a few days ago and I’d been replacing heater fan , radio , I took the cowling off , lubed the wipers and tried to figure out why it’s getting wet on passenger side.

I found the black wire from key goes to tgat relay , swapped it it has a J on it terminals were dirty , I think maybe it disables the seat heaters when cranking , or something

I could not find any wire that’s hot when key is in crank mode
I think it’s more complicated than I first thought it should be

I found two wires from key go through the park and neutral switch and loop back to another key terminal and that has continuity and seems ok

I’ll try to find a better schematic than Haines it shows a map of the key position connections but it’s too tiny and fuzzy

I have my spare harness and I’ll try to follow back from starter to figure out where it originates it seems to go through a big master plug so maybe I can break the problem in half if I can get to that , it’s like a 3D wiring diagram so im trying to understand how it works

I found very little on google about any explanation of the start circuit wiring

It’ll run if I jump the starter I think I can try tgat but I’d like to find tge cause

the problem is the wire to the starter is not going hot with key in crank position

Swapping key switches didn’t make a change , same symptoms

[740phil]

I found a Volvo 740 schematic here that’s for a year or so newer

https://www.nuceng.ca/bill/volvo/Volvo740wiring.pdf

If I’m seeing it right it show that the green with black stripe goes through the DS pillar plug, then the PS pillar plug and there is a test point plug, then enters the ECU

So I was thinking the cranking circuit was connected yo the wiring at the key , but maybe it’s actually driving the starter’s green wire through the ECU

It also looks like a very long path to get there , if I’m understanding this correctly

[740phil]

So in case anyone follows all this ;

Page 7 of https://www.nuceng.ca/bill/volvo/Volvo740wiring.pdf

LH-Jetronic , B230F

Page 8

Call-out 9 is the starter motor

Wire at starter is BL-GN

To “P” - connector, electrical distribution unit” It depicts a jumper, or similar

To “B” - “Connector , left A post “
pin 24

Through pink wire

To “A” - “ Connectir , right A post”
Pin 15

Through pink wire

To ECU , pin 30

- this schematic is a bit newer than my car , which is 87 or 88 but it is different from what’s in the Haines manual

I think maybe Volvo started to involve the ECU in the start circuit and perhaps older cars fed the starter motor trigger wire from the key wiring

I’m trying to document it , even though no one here is really able to help much .. might help another person who’s stuck
Phil

[volvolugnut]

Phil,
My Bentley manual for 240s up to 1993 shows a Blue-Yellow wire going to the Auto trans start inhibitor switch. There is a connector in the line and a pink wire continues to the pin 50 on the ignition switch. The connector is shown to be jumpered when a manual transmission is used. If you have doubts about the transmission start inhibitor switch, you could find this connector, unplug the wires to and from the transmission and jumper the blue-yellow to pink connector.
All this assumes the 740 is like the 240.
There is a test of the starter solenoid:
Test voltage at solenoid terminal 50 when switched to start. If less than 8 volts, look for wiring of ignition switch problem. Start solenoid could also be at fault.
volvolugnut

[Amazonphil]

Thanks volvolugnut

I think You fell down the same hole I did but followed the Bentley manual !

Now if you compare all that you said and look at this ,( below) you’ll notice the Volvo schematic shows power for the starter motor “trigger” fed from ECU not the key ..

Page 7 of https://www.nuceng.ca/bill/volvo/Volvo740wiring.pdf

LH-Jetronic , B230F

Page 8

Call-out 9 is the starter motor

Wire at starter is BL-GN

To “P” - connector, electrical distribution unit” It depicts a jumper, or similar

To “B” - “Connector , left A post “
pin 24

Through pink wire

To “A” - “ Connectir , right A post”
Pin 15

Through pink wire

To ECU , pin 30

[volvolugnut]

That is a much better schematic!
volvolugnut