Expert: Roger J.M. Warrington - 12/28/2006

Question
Dear Roger,

Please help me resolve this problem with my 2001 Impala 3.8L.  Intermittently the temp gauge reads 'zero' and, when the engine is shut off in that state, the cooling fans continue to run.

I checked temp sender & PCM input circuit; both seem fine.  I tested by disconnecting/re-connecting the sender while the temp gauge was mis-reading; it had no effect on the gauge's reading (IE - needle didn't move).

It might be helpful to know more about the faulty state of the temp gauge and my comment of 'reads zero'.  When the ignition is switched on/off the needle moves slightly.  But it never moves into the hash-marks on the gauge.  Not that this is a sporadic condition; at other times the gauge works fine.

Note that I'm not so concerned about the lack of the gauge or the cooling fans or battery drain (they shut-off after a time), but more concerned about secondary effects of the problem.  I recently had the transaxle replaced (ouch!), and the trans mechanic indicated there could be a condition where bad temp data could lead to mis-control of trans (torque converter), causing the converter to lock (unlock?) when it shouldn't, and ultimately busting the trans.

Thanks so much for the help provided through your expertise!

Pete

Answer
Peter;
Hi well as far as the fans it is normal for them to run when you shut the car off as long as they turn off in a few min.the gauge  is not working- it could be the gauge itself / or the sending unit for the gauge and it is a lot cheaper to buy.Have you looked at the sending unit to see if the wire came off of it ?????