Rear light goes off with the headlights

[RLambert]

Hi,

I've bought myself another C2 manual Coupe to play with and I'm sorting out a few litle issues with it.

One weird problem is that the n/s rear light works ok when the side lights are on but when I switch them to main it goes out. The o/s rear light is fine. Any ideas ?

The heater blower also comes on full when I switch on defrost but when I switch defrost off the fan doesn't stop. I need to turn off the ignition to reset it ? The heater all seems a bit complicated so any help would be appreciated.

Cheers
Richard

 

[bernard tester]

I would check for bad earth on the rear light, you can put another wire on to a good earth and check you can just attach the wire to the engine and on to the light body or push down beside the bulb! Yes the heater system is quite something! you will just have to check through piece by piece or if you know someone with a PIWES tester that would help. Regards Berny.

 

[Steve Brookes]

What happens if you just turn the fans up to full blast (number 4) and then turn it down again just using the dial instead of the defrost button?

Have you checked that the headlight bulb comes on when you turn the switch? My experience is that weird things happen to lights on the same circuit when one bulb on the circuit is out.

 

[RLambert]

I'll check the earth on the rear lamp. Yes, the headlight does come on ok.

As for the heater, it's acting strangely, yesterday for a while the fan went on and off correctly as you used the defrost or fan knob, then a bit later on the fan played up again. Basically if you turn the fan on by either means, it just goes onto full. Except it's not permanently full, you can hear it clicking somewhere and it slows down then speeds up, a bit like a rough idle !

 

[Steve Brookes]

If you put the heater on the blue dot and operate the fan speed and get the same effect it usually means that the problem is the final stage amplifier under the front scuttle panel - it has a large triangular heat sink and is fixed to the wall between the servos and the petrol tank.

If the fans behave normally on the blue dot but they act up when you select any sort of heat its normally related to the rear blower - fuse in the rear fuse box (should be 30 amp), the relay in that box, the ballast resistor or a problem with the blower itself. However, a problem here normally means you get no fans at all when heat is selected.

So many components makes these things difficult to diagnose!

 

[RLambert]

Here's an update...

Rear light, I took the light unit out and tested it again and it's working ok, so not sure what was up with that!

Heater, took all the servos out and replaced a couple that weren't working, I also lubricated the fans which were both very stiff and now it's all working perfectly. I think the stiff fan was overloading something so now it's free it spins up easily.

Thanks for your help.