So I've just finished swapping a running 960 motor into a perfectly fine S90 car. Everything is connected properly and all should be good to go at this point, however, when the ignition is turned over, there is no reaction from the starter.

When a 12v source is connected directly to the starter, the engine turns over.

The ignition system and starter relays have been replaced.

All related fuses have been checked.

It feels similar to when you try to start the engine while not in P or N.

The ignition will not turn the engine over when tried in any gear.

Used a brand new battery.

Alarm system control relay has been replaced.

The horn is also not working.


Anyone have any suggestions as to what the issue might be or where to look next?

Any help is greatly appreciated.

 

I think it may be the PNP switch, or the transmission linkage. Try moving the gear shift and see if it will turn over in another gear or neutral.

You are focused on the engine because of the swap, and it may be just coinincidence and either the connections to the trans or the switch itself may be locking out the starter.

DanR '94 964 387,000 miles (153,000 on the new engine)

 

I have read about a similar issue with the white block 850. If the mating surface between the motor and transmission isn't clean when assembled, it doesn't make sufficient ground connection and won't start. I know it sounds strange but a few people had this happen. Pulled the motor, cleaned both surfaces with a wire brush, put it back together and bomb, all good.

This was usually an issue if either part was exposed to air for some time, ie: motor sitting around for a few months or the car sitting around for a while with the motor out.

Another note: several failed attempts were made to ground them together with wires, ground straps, etc.

 

We've tried starting the ignition in every gear with no luck. Everything else seems to be working accordingly, when you put the selector in reverse the reverse lights come on.. etc. We've looked over the linkage, everything seems to be hooked up properly. Can you tell me more about this PNP Switch?

When we swapped in the new motor, we also swapped the transmission from the 960 as well. The motor and transmission were never separated. One thing to note is that the engine is currently not bolted down tightly onto the motor mounts, they are just hand tightened "snug". I believe the transmission is also just hand tight on the crossmember as well. (keep in mind we could turn the motor with a direct 12v source to the starter)

Is there any chance this is affecting the ground of the transmission/motor?

 

I'm not sure if those mount have any grounding straps on them or not. Not sure why it's not cranking unless you have a bad cable somewhere from the battery to the fuse box or something like that.

 

Does the engine turn over by hand?

The PNP switch is kind of like a neutral safety switch and gear position sensor. Having reverse lights may not rule out a faulty switch.

DanR

 

The engine does turn over by hand (the wheels did not move when engine was turned).

I've been looking into the PNP, is there anyway to test the switch with or without removal?

Thanks thus far!

 

Did you ever get a fix for this?

 

I sure did but unfortunately I have no idea what exactly was done to fix the issue. We ended up taking it to a specialized Volvo shop who looked over it for about 2 months and eventually connected a wire from inside the wiring harness to a terminal near the transmission. Apparently the 960 and S90 differ in the way the "hot" gets to the starter. If I find out what was done I will post.

On the other hand, the motor/car combo works great!