1998 Jeep Grand Cherokee Electrical Problem

I'm having difficultly determining where the problem is in my 1998 Jeep Grand Cherokee.

Symptoms:

Engine RPM drops randomly while driving (typically this happens when I let off the gas or when the cruise control lets off the gas, the RPMs will suddenly drop dramatically, then bounce back up after usually one to three seconds)

Dash lights dim, sometimes almost out completely, then brighten up again.

Radio controls - when adjust the bass, treble, mid range the small yellow light on each control which is usually steady, goes out while I make an adjustment. After making the adjustment the light brightens back to normal. Rest of the dash lights appear unaffected.

I'm wondering if something is grounding out somewhere, or would the alternator cause this, or is the PCM module the more likely culprit?

Any thoughts would be appreciated.

Reply to
wisconsin262
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Could be a dirty throttle body and automatic idle speed motor. Clean with fuel-injector cleaner and a shop rag.

Concurrently with the RPM drop? Just the alternator can't keep up at such low speed.

Completely unrelated to anything else. That's pretty common on those radios after they start to get some years on them. It'll eventually get to where the little yellow light won't come on even when you're not moving the equalizer sliders. It doesn't affect radio performance, though.

Reply to
Steve

Sometimes concurrently, sometimes not. Usually not actually. And, when I adjust the dimmer switch the lights will flicker... dimming and brightening, and then settling on the new adjustment. Adjusting the dimmer does not appear to affect the engine RPMs. The RPM occurs after letting off the gas.

Reply to
Jeff

Then I'd guess the dimmer control is just dirty, like the contacts for the illumination lamps in your equalizer knobs. Does the interior of your jeep see a lot of humidity? Parked outside at night?

As for the RPM drop- clean the throttle body and AIS.

Reply to
Steve

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