Diagnosing radiator fan won't start

[H286]

I've moved my discussion into a separate thread from http://www.astra-mk2.com/forum/forum...2-fuse-diagram

[H286]

Currently the Radiator has stopped kicking in and bypassing the thermal switch does not activate it. Will check fuse next.

I powered directly the fan off the battery and it spins up nicely. I need to check the thermal switch output with a multimeter to verify the resistance at temperature. The fan was working fine a couple of weeks ago.

[H286]

With a multimeter I can see that the path from ground (-ve) to the fan is intact and there is continuity.

With the connector that goes into the fan(not the connector coming out of the fan) there are two terminals. One is from the thermal switch and I believe the other should be 12v. However with the ignition on and the multimeter set to 20V I cannot get and potential between the 12v terminal and the -ve of the battery. I will repeat this test again in case I have made a mistake.

The horn is working which shows that +ve is coming in to the top of the circuit and the fuse is not failed.

[H286]

Here are some pictures. I phrased wrongly in the above. Instead of "... there are two terminals." "I cannot get and potential between the 12v terminal and the -ve of the battery." I meant "...there is a socket with two connections." "I cannot see any potential between the 12v connection of the socket and the -ve terminal of the battery." (The socket is in the second image)


The thermal switch connector with Gnd identified:


The socket for the radiator:

[H286]

Did some move investigating today. Definitly the 12v into the motor is not energised. The circuit is active because I can toot the horn at the same time. Will find the point where the horn +12v and the radiator +12v diverge.

[DarrenH]

you seem to be working it out yourself but yeah there should be 12v at the 2 pin plug, are you trying with the ignition switched on ?

[H286]

Yeah ignition on, The car does have an imobiliser but that shouldn't affect the operation of the fan. The wiring from the plug that has the 12v looks fine and doesn't appear to have been abused. Will check the reading again and confirm.

[H286]

Do you know how accessible connector X6 is? Connector, body and instruments. It seems to make sense to check the voltage and continuity of the connection to the top of the fan from that point if it is easily accessible?

[DarrenH]

not sure where X6 is, might be the huge junction in the passenger footwell (behind the plastic on the A pillar)

[H286]

I am going to double check the thermal switch is working at temperature.

[H286]

Some progress.....

With the airbox out I took a closer look: I could see some bare wires in the coolant switch wiring and then noticed the wire is 'crunchy' .

The plan is to replace the wiring and connector to the point where it comes out the main wiring loom bundle.

Is the thermal switch connector an EV1 connector? It looks like it is? Says AMP on it which presumably stands for AMPHENOL.

I had what I thought was an EV1 connector but it didnt fit for some reason.

[DarrenH]

looked at my gte and merit, they are nothing like minitimer, the pins inside are as big as a spade connector!

[H286]

Yeah its should be whatever connects onto this:


The coolant switch is the same connector as this.

[DarrenH]

H286 just revisiting your photos from jan 2020 (eeeeek) and got myself a bit confused

your photo of the minitimer with GND written on it is for the ECU temperature sender (in the thermostat housing)

the radiator has its own thermister screwed into the end of the rad, at the battery end, and plugs into a beefy waterproof plug somewhere between the battery and the headlight.