Auto choke relay

[edmil]

The auxiliary fan on my CSA is coming on when I start the car, rather than when it is needed to cool the radiator. I think I have tracked the problem down to a faulty auto choke relay.

The relay which came with the car when I bought it is a Bosch 0332 100 020 which has 4 terminals- 85/86/87/30.

W&N, Jaymic and BMW parts do not seem to sell a replacement and I have not been able to identify a BMW part number to try to track one down. The Bosch part number has long been superseded.

Does anyone know if I can use a standard 30amp 4 blade relay as a replacement

 

[HB Chris]

What year is your coupe? Only 74 got the relay and extra temp sensor to turn on fan with A/C. There is no tie between that fan and your chokes so that is strange. That relay is a standard configuration also.

 

[edmil]

Hi Chris

The car was first reg 5 Jan 1973, is presumably late 1972 manufacture and does not have air conditioning.

I have attached a copy of the wiring diagram from the workshop manual which is dated 12.71. This shows the relay bottom left item 117 and other information I have indicates that this was probably an optional extra.

The relay is an NC (normally closed) type, probably the only one of this type on the car.

I have identified a Durite 0-727-02 which appears to have the same circuit but would like to be certain it is a direct replacement before fitting

 

[HB Chris]

I looked at my wiring diagrams from the blue books, the choke relay is not related to the fan in front of your radiator which I have never seen on a non A/C coupe. The choke relay is triggered by a temp sender under the intake manifold. The relay was not an option, it is on all coupes with Zenith carbs and receives switched power until the temp sender opens the ground.

On an A/C coupe the fan relay is under the coil on the inner fender and sends power to the fan from a large 12g wire directly from the battery in front of the radiator.