I bought this 91 Supercab shortbox F150 4x4 with about 100,000 miles on it a while back and everything but the temperature guage worked awesome.

1.About three weeks ago the intermittent wiper function stopped working, then about a week ago the regular speed fulltime function just quits randomly. If i smack the steering column or dash it takes off again but then soon quits and we play this little game over and over.

2. A couple days ago the speedometer decides to only go part way and bounce around and has slowly died as well.

3. Also the day before yesterday.... the marker light/dash light function quits! I figured it was the switch so i have since tried two other switches. While doing so, i discovered that if i pull it all the way back so the headlights come on then push it pack in between the two positions... the marker/dash lights come on as well but go off in their specific position. ALL 3 switches seem to do this... WTH?

Its driving me crazy... Oh heres another one:

4. The heater only works on full blast so i changed the resistor as instructed by everyone i asked... and that wasnt the problem. Before i go ripping more of the dash apart to change the SWITCH... any ideas?

 

have you checked all grounds? in many cases a multiple function problem with the electrics can be a bad ground-I know it sounds crazy huh

 

grounds between your body and frame are corroded. clean them, and add a 10 ga wire from one of the wiper bolts under the hood to the motor some where. also add a 10ga wire from the neg post of the battery to the core support where the radiator bolt is. there was a tsb on this a while ago, I forget the number. good luck, let us know how you make out. I have a few more things to try if that don't work.

 

thanks guys, i'll be trying that asap... i kinda wondered about a bad ground but i never really considered that i guess because its never happened to me before.


Dam canadian road salt!