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RE:ISV Starting Problem?

On Thu, 19 Jun 1997 11:52:58 -0700, russ southerlin wrote:

>Does anyone know where the ISV Thermo Switch is located. My schematics
>show a Blu-Grn wire from the ISV Stabilizer Control Unit pin 13. I can't
>find it anywhere on the engine - What gives.

Look on the left, front side of the head, slightly below and behind the
pump mount. If that's not the sensor where the Blu-Grn wire is connected, then
look on top of the cooling hose flange a little further back.  Here we have the
makings of a mystery since the thermal sensor at each of these locations
seems to be the same part number in the few 87 and 88 5kcstq cars I have
inspected. Neither is an open/closed _switch_ as suggested in the Bentley
electrical drawings and elsewhere. Both are _sensors_ with a resistance which
varies gradually with temperature. One is for the ECU, the other apparently for
the ISV controller. The fiche seems to confirm this.

I have played with pretending the ISV sensor was a switch by connecting
the Blu-Grn wire to ground for a cold engine and starting improved. My
theory is that something fell into a crack during production of these cars.
If anyone else has some thoughts on this, I'd love to hear them. Best regards,

DeWitt Harrison   de@aztek.com
Boulder, CO
88 5kcstq