Electrical problems with oil pressure gauge blower motor idle speed

Asked by Guru95TBRJ Jan 01, 2021 at 08:26 PM about the 2004 Chevrolet Trailblazer LT RWD

Question type: Maintenance & Repair

The blower motor has always operated  strange  sometimes  the lower
speeds would work and hi spd wouldn't and visea versa the hi would work
and the lower spds wouldn't today it was stuck in hi spd  and wouldn't turn off
even when I shut her down ,took the key out , had to pull the fuse the blower
j case fuse I also have the check gauges lite coming on and when it comes
on the oil pressure gauge drops to zero  you can get i to stop by increASING
THE IDLE SPEED  THE IDLE SPEED IS IRRATTIC TOO WHEN ALL THIS
IS HAPPENING DUE TO THE AC COMPUESSOR CLUTCH TURNING OFF
AND ON ,ITS LOW ON FREON I TRIED TO ADD SOME BUT THE IDLE
WAS TOO BAD  ALMOST DIED  WHAT IS GOING ON? I don't think its an
oil pressure issue it feels more like an electrical one. what are your thoughts

5 Answers

26,640

this for blower motor. Make sure battery has a full charge and connections all good. See the top right fuse in diagram, that is for hi speed only, hi speed doesn't use a resistor. In the diagram, see the blower relay, The relay has to be energized to have continuity for hi speed. when relay is not energized, continuity for lower speeds. The relay has two sides, the load side, right side in diagram. The control side, left side in diagram, the control side needs voltage and ground in order to energize relay. The blower wiring connector, with key on, blower controls on, blower motor not working, unplug, use both ends of test at connector terminals, if the lamp comes on, you have voltage and ground good enough for test light, but, if there was no blower action when plugged in, I'd probably suspect the blower motor is faulty. If the brushes in blower motor get worn down, the motor may run intermittently. I can only help with testing.

26,640

as far as idle, found this service bulletin. your year--make--model was included. If you have tac/throttle actuator control, any trouble codes for that system. when cleaning, my thought, don't force the throttle plate. good luck.

11,195

On the 4.2 engine....for oil pressure gauge problems, look to the oil pressure sensor, located right above the oil filter. I'd replace it, if it has oil on it, it's definitely bad. Showing no oil pressure on the gauge can cause problems, like a reduced power engine, even though the pressure is sku'd by the faulty sensor, not necessarily bad oil pressure. Common problem. For the blower motor....another very common problem. Replace your blower motor resistor or blower motor module, AND the pigtails that go with it. Important note: manual controls use a blower motor resistor; auto controls (digital) use a blower motor module. Both look the same, but will not work if you don't get the right one, one won't work in the other and are not interchangeable. Again, very important to replace the pigtails too, as they melt inside. Finally, to Oilspills point, doesn't hurt to clean the throttle body, should be done at min. once a year anyway since we don't have a traditional PCV valve, which causes the throttle body to gunk up quicker than normal.

Best Answer Mark helpful

I fixed the blower motor problem, it was the resistor. as far as the oil pressure dropping to zero I have noticed hearing a spark click coming from the back of the engine, close to the throttle body, when it clicks thats when the idle drops and thats when the oil pressure drops Everything seems to be operating fine when cold its about 10 minutes when it warms up that this problem starts to happen

11,195

Very well could be the throttle body butterfly doing the clicking. At minimum, rip it out, (4bolts). Remove fuses # 10 and #28 under the hood. Then remove throttle body and clean it. Also, check the connector and the wires connected to the throttle body, and check the wires (harness) going back towards front of the engine from that same connector. Any check engine lights?

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