Chrysler Repair: 1992 LeBaron Intermittent tachometer, turn sigs dont cancel, engine management computer, odometer units

Question
Tach works whenever it wants to.  I can't seem to find a pattern.  Have replaced tach drive module on instrument cluster as well as entire tach unit and engine management computer under hood on drivers side.  Also speedometer/odometer units are less intermittent.  Both are electronically driven but from different sensors I believe. Once speedometer begins working it stays working.  Tachometer can start working and stop working at any given time.  Could the Body Computer located behind the right kick panel be giving me these intermittent problems?  Also turn signals won't cancel on this car.  Have replaced both ignition switches and can hear pawl switch activating when it contacts the plastic post as the steering wheel cancels each turn.  What's next?  Thanks Tim

Answer
Hi Tim,
I would look over the circuit board and the connections between it and the plug sockets for cold solder joints. Particularly look at 8,9,14 of the red plug and 6 of the black plug. Then when you don't have tach function check for 12V on pin 8 of the red connector, when the ignition is on check for 12V on pin 9 of the red connector, and verify ground on pin14. Using an AC voltmeter check for 1V or more on pin 6 of the black plug when the engine is running, and if not check continuity from 6 to pin 43 or ecm. Other than that it is replace the drive module or the tach itself, which you already have done.
The body computer has nothing to do with the tach.
The turn signal cancellation is performed by a cancellation switch and a cancellation solenoid. There are tests for both units, but the text for these is too long to type in here. Let me know a postal mailing address and I'll xerox copy and postal mail the procedure to you.
Roland