Hey all. looking for some imput here. When im in park and at idle , seems to be 6-700rpm. Nice and steady. But when i turn my lights and fan on while at idle the lights will dim and rpm will drop for a moment then steady back out and this cycle will repeat about about every 10-15 seconds. Is this an alternator issue or something else. This is driving me nutty. Any help or direction is greatly appreciated. Thanks

Check pcv for clogging

thanks Renkj, pcv is new, engine is well maintained oil changed regularly. No codes at all. just seems like to much draw for that rpm at idle. Not familiar with all the sensors involved with these . maf is cleaned, throttle body is cleaned as well.

Check the alternator voltage output, should be around 14,run the engine, have your buddy run the hvac and lights and monitor for voltage drop

Sorry about the delayed response but I just got this on my phone. Anyway I went to Autozone today and alternator has a bad regulator under full ac load . Also changed the IAC valve and that helped bump the rpm up to 600 rpm witch is better than 500. So now I am debating about the alternator and from what I am reading theres a debate about the high output vs 136amp. Point being the pcm will cut the amperage to 136 even if its a 160 or 200 so there will be no benefit. Unless you get the PCM reprogrammed. AS I live up North the winters get cold and and all my defrosts, seats rear defog, lights ,fogs etc are running most of the time I need to figure something out.


Any solutions are appreciated.

See if a dealership will flash you with the renegade PCM which will set you up for the higher output 160amp which they come with

This may sound strange, but, check your electric radiator fan...I'd noticed for a while that when stopped in traffic that my idle speed would suddenly drop 300-400 rpm, then pick back up again... The high speed circuit of my cooling fan went out last week...After replacing the fan the RPM drop while stopped in traffic went away...My guess is that the resistance of the fan motor was becoming greater and greater, as it was on it's way out...More resistance was creating more of an electrical load on the alternator, thus the drop in RPM...

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Black '05 Renegade. Front suspension: Frankenlift, Moog HD LBJ's, Audiboy cut CV's
Rear suspension: OME 948's, 2 extra upper ISO's, Rancho RS 5000 shocks.
31X10.50X15 Duratrac's/ProComp 152's
ARB bumper, Mopar skids, JCR stage III's, Reese hitch with tractor lights, Champion shackle insert, "homebrew" on board air, 1000 watt inverter