Re: coolant temp sensor

[Phil Rose <pjrose@servtech.com>]

>Phil Rose wrote:
>>
>> The ACC diagnostic channel 01 ('89 100) has always produced an 09 code,
>> which I have ignored until recently. According to the Bentley, the 09 code
>> means a faulty "engine coolant sensor"--the one that's inserted just upside
>> the large coolant hose/thermostat flange. I ran the electrical tests and
>> everything appears as per specs--both the sensor resistances and the
>> voltages at the connector pins. So...why does the ACC tell me there's a
>> problem here?
>>
>> According to the manual, the symptom of a defective coolant sensor will be
>> hard cold-starts and rough running during warmup. I've never noted the
>> former, but the latter symptom is sometimes present in winter. Is it
>> possible that the 09 code from ACC channel 1 of '89s is not meaningful?
>
>That does seem to be the case, the coolant temp sensor G62) they refer
>to was phased in on the later 200's, the 1991 200TQ 20V has this sensor
>incorporated into the heater valve at the back of the engine. The
>Bentley on page D8-310-1 explains this phase in of this sensor. I
>believe, this sensor is used to ensure the engine coolant is warm enough
>before the interior fan is turned on. I think the earlier systems used a
>standard time delay after start up to accomplish the same thing.
>
>HTH
>--
>Scott Mo.

>I can check my '89 100Q, but I seem to recall it gives me 09 also,
>and Bentley says this was a running change. Some 89's don't have
>some sensor.
>
>--
>
>Andrew L. Duane (JOT-7)			duane@zk3.dec.com


Scott,

I thought my car's two-pin sensor located above the coolant hose is
G62--not so? G62 sensor was presumably phased-in during '88 production ('89
model year?), so it seems reasonable that my '89 100 has it. But... Andrew
says he gets the same 09 code, so if his car ('89 100q) has that same
sensor, my guess is the code is not meaningful.

Phil

Phil Rose		Rochester, NY
'89 100
'91 200q		pjrose@servtech.com