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91' k2500 WEIRD problems

Discussion in 'Chevy Trucks' started by AmPlower, Mar 5, 2003.

  1. AmPlower

    AmPlower Junior Member
    Messages: 15

    Hi all, I've been having this problem lately, when I turn the heater on, the speedometer will freeze where its at, a couple minutes after turning the heater on. However now once the speedometer freezes, the engine just rev's..I loose drive and overdrive and sometimes 2nd, usually almost always have first though. The check gauges light comes on when the speedo freezes, and the tranny seems to function OK once it goes off, however lately the tranny doesnt seem to shift that firm. just 1st-2nd it shifts firm then it just slips into gear from there on.

    2. My left hand turn signal only flashes once when the lights are on, So I manually flash it, and my brake light is on as well, and when I manually flash it, the brake light will alternately flicker, oppisate of the turn signal flashing.

    3. And my running lights come on when the brakes are hit, even when the ignition is off.

    I'm starting to think my cluster is messed up but I dont know where to start now. Please help.
  2. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    Just a guess here,but i think you have a bad ground somewhere, and whatever it is that is in need of a ground is going thru other circuits to get its ground,this can play havoc with the truck.Id start with the heater motor,since its the source of all the problems. id check the motor ground,clean it,and make sure the wiring is not rubbing thru to any other wires. also there are usually grounds at each corner under the dash where the dash assy bolts to the cab,check those they sometimes loosen up over time.I had a slow power window motor and a lazy power lock actuator on my 92GMC 1500,that was the problem,tighten the ground everything worked great again.
    Last edited: Mar 5, 2003
  3. Alan

    Alan PlowSite.com Addict
    Messages: 1,393

    And now, Page Two

    This is no help to the original thread, but I've got gremlins in my 88, K3500.

    Oil pressure guage has been flaky since I got the truck, pressure bounces around for no apparent reason. On Monday I noticed it was hanging right around 15 psi, lower than usual, and rock steady regardless of RPM. Tuesday morning I hheaded after a load of sand and happened to be looking rihgt at the guage when it went to virtually zero and the idiot light came on. 0 Dark:30 and brutally windy, I dumped a couple qarts of oil in and no change. Nary a bad sound from the engine so I got off at teh next exit and came home on the two lane at about 40. 10 miles and still not a bad sound and never showed more than 5 psi.

    Got it into a shop today. They put a test guage on it, 28 psi at idle, a little over 30 at high idle. Not great but they can live a long time on that much. Assumed bad sending unit, replaced it. Problem is still there, just about zero pressure, no noises. On a cold start it shows 15 psi (was showing 30ish right up to Monday)

    Let it set for 20 minutes (not long enough for the oil to be cold)and it shows 15 again for about a minute then drops back off the scale. Every once in a while you see the guage jump and the light flicker. When it jumps it comes way up but only briefly.

    I'm going to install a mechanical guage this weekend as a double check. This one has me baffled.
  4. Lawn Pro Enterprises

    Lawn Pro Enterprises Junior Member
    Messages: 5

    also could be a rotten trans wireing harness
  5. speedracer241

    speedracer241 Senior Member
    Messages: 325

    Check the tail lamps for the lighting problems. The sockets corrode internally and cause all kinds of "odd behavior".
    I worked on a Chevy a while back that the turn signals were feeding power back thru the trailer break controller.
    The bulb socket screws into the tail lamp housing and plugs into the wiring harness. It is a pretty common part at the parts stores around here.

    Good place to start,
    Mark K
  6. wyldman

    wyldman Member
    Messages: 3,265

    Like speedracer said,check the rear light sockets.They are mounted on a circuit board,which corrodes and causes all kinds of problems.There are updated ones available.