95 volvo 850 - wiggle engine cooling relay fan, engine stops

850brat · Post by **850brat** » 23 Jan 2023, 08:19

When I wiggle/move engine cooling relay fan, the engine stops running.

I have the wiring diagram for the engine cooling fan and relay.

Can somebody explain how that occurs?

Thanks

Post by **Chuck W** » 23 Jan 2023, 09:02

Are you wiggling the fan relay, or the main FI system relay?

Both are located above the radiator. The fan relay has 3 plugs and on the pass side of the car. The FI relay has a single plug and on the driver side.

850brat · Post by **850brat** » 23 Jan 2023, 09:56

It's the fan relay, 2/11 on wiring diagram.

Post by **Chuck W** » 23 Jan 2023, 15:18

Unless you're getting some weird backfeed into the ECU through the fan control wiring, I can't see anything that would cause the engine to die.

Unplug the trigger wire connector (with the two small wires) and see if wiggling the relay causes the stall. (Don't run it too long, seeing as you have the fan disabled).

Post by **scot850** » 23 Jan 2023, 16:30

The wires can get crusty under there and the wires can split and potentially cause a short that may cause a feedback, but as Chuck says, can't think why that fan unit should cause the engine to stall. Try what Chuck suggests and look really closely at all the wiring connectors and their respective wires for issues. You could also use some electrical tape and feed it between the wires temporarily to see if that stops any potential wiring shorts at the connectors when you wiggle the relay.

Neil.