e32 Jet Heaters

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Rick - 09 Jan 2007 11:52 GMT

I have a 1994 740iL. Can someone tell me what is the setpoint or what
causes the Aux Water Pump, Jet Heaters and Windshield defroster to turn on?

I am blowing fuse 9 and IHKA sends a signal to the water pump relay which
controls the water pump, jet heaters and windshield defroster but at what
point or temperature does the relay energize?

I have operated the car with the aux water pump disconnected but fuse 9
still blows and I lose the horns. I am suspecting a shorted jet heater. Is
there any known ohmic value for these heaters?

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John Burns - 09 Jan 2007 12:22 GMT

> I have a 1994 740iL. Can someone tell me what is the setpoint or what
> causes the Aux Water Pump, Jet Heaters and Windshield defroster to turn on?

I believe the aux water pump is always on (unless the heater is off
perhaps). had to replace mine recently (e38 730i v8), not a major job.

The jet heaters on most modern BMWs use a sensor in the brake duct to
turn them on, but earlier models had them on all the time! I think the
E32 uses the sensor.

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Dan Buchan - 09 Jan 2007 23:41 GMT

>> I have a 1994 740iL. Can someone tell me what is the setpoint or what
>> causes the Aux Water Pump, Jet Heaters and Windshield defroster to turn on?
> The jet heaters on most modern BMWs use a sensor in the brake duct to
> turn them on, but earlier models had them on all the time! I think the
> E32 uses the sensor.

I have a 1997 E39 and apparently the washer jets are always on, they use the
natural property of increasing resistance with temperature to heat up a to a
certain point and stay there. I haven't checked this, I don't even know if
they work, but that's what the book said.

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