I went to fix the Temp Gauge on a 240 the other day. It was bottomed out. I started at the temp sender and did all the checks (sender resistance, integrity of wiring, loaded circuit with 68 ohms, etc.) I concluded that the problem was in the instrument binnacle. I pulled the instrument pod and first checked the voltage regulator because the fuel gauge was also almost bottomed out and I thought that maybe, for once, my son had filled up the car. The regulator was OK. The last time I had a similar problem with a 240 temp gauge, all it took was cleaning the temp comp board terminals so I did that and I also reflowed a pin on the instrument circuit board which looked suspect.

Plugged it back in, loaded the curcuit to 68 ohms and all seemed fine. After I buttoned up everything, the gauge was back to zero! Now, in the mornings the guage read fine, in the afternoons it's zeroed.

I avoid R&R troubleshooting as much as possible; I've wasted too much time and only confused matters whenever I have not. So, how can I test the Temp Gauge Temperature Compensation board?

Rich