Hey im having sputtering issues. Miss firing issues was told it was pcm. I mean she drives good. I have to put it in neutral when its running n im at a light n then put in drive. I have to keep gas in over 3/4. I was told it has something to do with pcm. Ive changed out everything .From cap rotar. Plugs wires etc. She sounds rough. But u can still drive it. I have a new computer for it. Should i get that reprogramed. The abs n check engine light is on too. Just wosh i knew the issue. I love the jeep n want it to run smoothly. Other than little oil leak nothing else major .What do i do. Everything is new except for crank shaft. Pistons. I was gon get a new motor or put in a souped up motor. I want to keep this jeep n run it. Can u plz help me. Should i have new pcm programmed to jeep vin. Rest one thats in there. But its taking chance of something else. It make a little sound. Like a sreecth sound n speedometer n rpm guages jump like crazy time to time. But like i said she runs n drives but very rough. I went to you tube. Got connecter spray n cleaned em. N still see a little differnt but not much. Thanks what do i do.

 

What year, engine, etc? Stop by Autozone or other auto store that will pull the trouble codes for free. The PCMs rarely go bad.

 

I cleaned my throttle body n the 3 sensors there and went from 16mph to about 21 mph and it only took about an hour

 

This worked for me, thank you!

I have a problem with my 2011 Jeep Grand Cherokee where it sometimes just goes dead. There is no lights on, and the ignition doesn't work. The door locks do work and the headlights work but everything else is dead! The dashboard lights don't work and the car will not start. It won't even make a sound and the interior lights will not come on. Resetting the ECU seems to be the only thing that works.

Now I carry a 10 millimeter socket and ratchet in my Jeep at all times so if the ECU acts up when I'm out and about I can just disconnect the battery, hold the break paddle down and then reconnect the battery.

 

I just purchased a 97 RHD postal jeep cherokee. 4.0 auto. It has sat for over 10 years. I believe the ecm is dead. Can I just swap it out with a junkyard ecm and do a basic reset on it? Or does it have to be programed with Vin # and other stuff?

 

What makes you think the ECM is dead? That's usually the last thing on the list of possibilities.

 

Not getting any signal to obd port. No odometer, no no bus signal, just nothing. I have to do the 5v lead test first, but I'm leaning towards the computer. This cherokee has sat for over 10 years. The last two with the hood open. So the computer was subject to rain snow and all kinds of weather. I'm just planning on worst case scenarios.

 

Yeah, I think verifying power at the ECU and sensors is a good place to start. Sitting for 10-years with the hood open, it's also very possible you have rotten battery cables and critter damage.

 

hello. I am totally new to this forum and psyched that i might be able to get some help. My 1999 XJ 4.0 is having a weird issue and i cant track it down I found this thread by searching for "Cherokee computer reset". When i turn the key to start the engine, i just get a click. Try again, not even the click, just nothing. So i followed the 'reset' by disconnecting the + battery cable and grounding it. It then starts fine and runs great. If i park it, it MIGHT start up again, but now it requires the reset probably about 1/2 of the time. I did get a new/rebuilt "plug and play" computer module and that seemingly fixed the problem for about 6 weeks. Now it is back and probably worse than before i changed the computer unit. The check engine light does not come on, unless it is in the 'accessory' position on ignition. If and when it starts----no check engine light. I show no codes on the OBD. Its really, really weird that the reset gets the engine started, but it just doesnt stay 'reset'. Any advice is greatly appreciated......thanks!

 

Oh man, I wish you would have found us sooner before swapping the computer. If it's not cranking at all and just getting a click, that's not the computer. I would suspect the neutral safety switch first. Does it crank if you put the shifter in neutral and move it around?. Then maybe battery cables and the starter.

Here Bleepin Jeeps tutorial on removing and cleaning the switch. The hardest part is getting it off without breaking it. The back side is plastic, so careful prying on it.
https://bleepinjeep.com/video/how-to...safety-switch/

 

Thanks for the reply......I will try the Neutral switch for sure. But, why would a 'reset' procedure change the NSS position? Or is it sending a signal that is also reset? Of course right now, it starts fine without doing anything. Im sure that will change when its 0 degrees out and im in a dark parking lot. thanks again!
skriv.

 

Messing with the ECU or "resetting" shouldn't do anything. It's possible the battery connection is crap and it's just the fact that you're messing with it that temporarily helps? Do the interior lights die when you try cranking, which would point to a battery connection problem?

 

thanks for the reply....i really don't think it's the battery connection. If i put cables and another battery on it, still nothing happens. I tightened the battery terminal, tapped it with a hammer, didn't change anything. Battery voltage is at least 12.5 V. Also, when this problem is 'active', no lights or any other electrical stuff comes on. Moving the shifter to N and shaking it around didnt do anything unfortunately, but i appreciate the suggestion on that.

Im sure if i do this reset again, the engine will start. I've reset it at least 20 times now. I had the throttle position sensor changed, but the problem didnt go away. Someone once mentioned (on a different thread here) that "if disconnecting and reconnecting the battery + cable allows the vehicle start, then it's a sign of a loose connection somewhere". No idea where that loose connection might be and i'm running out of things to check. Anyone know if the crank position sensor might cause this no-start problem? thanks guys......skriv.

 

You should also check/clean the battery cable connections at the starter and the ground connections. Make sure the terminals are clean and solid, especially the one on the block. Perhaps even replace the cables.

Bear in mind that the PCM is not involved in cranking the starter. So the "reset" itself should not fix it, but the act of connecting/disconnecting and moving those battery cables about may improve a connection and allow it to crank.

When you can turn the key to start and hear a click but no cranking happens, it likely shows a few things:
You're getting power to the ignition switch, the ignition switch is ending power to the starter relay, the starter relay is grounded through the NSS and the starter relay has energized. (hence the click)

What should occur now is:
The starter relay then closes the contacts to send 12v to the starter solenoid. The solenoid energizes and drives out the bendix to engage the flywheel/flexplate, completes the contacts for the starter motor (high current) then spins the engine over.

This assumes the proper volage and current flows through all the circuits. A weak battery, bad cables, corroded connectors, blown fuses, weak starter, bad NSS, bad grounds, etc. can all interrupt this process. They key here is to eliminate each possible cause from easiest to toughest to test based on the symptoms.

 

Thanks Saudade.....I will check all of these things tomorrow. Since i'm an engine moron, can you tell me if the starter relay resets itself when power is disconnected (pos battery terminal)? Could it be as simple as a relay replacement?