Relay burnt out?

[RWB]

Trying to identify various wiring modifications made by POs. The relay board behind the glove box is a mess, one of the relays appears to have burnt out and a second is permanently stuck on and the attached wires do not conform to the wiring diagram at all. The third seems to be working correctly.
Is this a typical issue on Stags? See pictures. IMG_7761.jpg IMG_7781.jpg

[NeilR]

Are you sure they don't conform to the diagram ?. The do if you look at the MK1 diagram, that relay is for heater blower & heated rear window.
I wouldn't have said it's a mess either, looks very tidy.

[RWB]

The lower center relay does conform but the relay on the left does not conform to the Haynes wiring diagram I have for Mk2 Stag. The right upper relay clearly needs replacing. The heater blower and heated rear window have bypassed the relay and is fed from the brown cable dangling in front of the relays that has been connected to the purple for those two functions. It looks neater in the picture than in reality.

[Philip Wardle]

The normally open contacts C1 and C2 on the relay with the burnt-out terminal are closed when the ignition switch is operated, i.e. + 12V is applied to the relay coil via the white wire on terminal W2, with the earth connection being made via the black wire on terminal W1. Terminal C1 is connected direct to the + 12V battery terminal via the brown there is no fuse. Terminal C2, which is missing from the relay, should supply the heated rear window via a purple/brown wire and the heater motor. These loads are protected by the fuse at position 21/22 on the fuse holder, this is rated at 25 amps.

It is difficult to be certain, but it looks like the purple/brown wire has been linked to another source of +12V which is inappropriate, so a good start would be to replace the relay and return the purple/brown wire to the correct C2 terminal.

On other cars I have seen signs of overheating around the C2 terminal, I guess these could be due to either high resistance between the tag of the terminal and the rivet by which is attached or high resistance between the actual C1/C2 contacts within the relay. The high resistance can arise due to corrosion over decades, and with the relatively high current drawn by the heater motor and heated rear window, quite possibly both at the same time during winter, there will inevitably be a heating effect.

C2 terminal.jpg

[RWB]

Thanks Philip, thats exactly what I intend to do.

[RWB]

Hi Neil, you are right! I was looking at the wrong relay. Correct me if I am wrong but I believe the left relay is the horn relay. The colours of the cables do match the wiring diagram.

[NeilR]

Yep, thats correct.

[NeilR]

Is yours a MK1 or MK1.5 ?

[StagJonno]

That purple wire connector at the bottom of the second picture needs the insulating sleeve pulling back to protect the live parts (possibly needing some additional insulating tape to cover all live parts).

[RWB]

Hi Neil, I have only had it since november last year and I believed it to be a Mk2. However certain things have made me wonder. The heads are Mk2 according to the numbers on them, the inlet manifold is a Mk1, the pulley, viscous coupling and fan I just replaced are all Mk1 (I replaced all 3 components with Mk2). The door locks are Mk2, wheels are Mk 2 but I am not sure they are originals. The hood is a Mk 2. The chasis number is LD31013A and according to Rimmers lists it would then be a 1974 Mk2 with BW65 auto gearbox. It also has a clock rather than an oil pressure gauge. So I guess its a Mk 2.

[RWB]

Hi StagJonno, yes I know. It's a work in progress but when I fit the new relay those cables will be fitted to their correct terminals and new insulated connectors fitted where necessary. I have been replacing many poor connectors already as I find them.

[NeilR]

I had some involvement with a MK2 that had MK1 wiring, it was all original. Shell & doors were MK2, dash, bootlid, rear bumper, all wiring was MK1, it was all original.