b0dini

Ok, so I've poked around and found some posts that are similar to my problem but nothing matches. Hoping you guys can help.

I have a 2004 Grand Cherokee Special Edition, 4.7L V8. Occasionally, it will not start, but does crank. It is an intermittent problem, but has become more frequent the last couple of weeks. Usually, if i wait it out 10-30 minutes, it will finally turn over, but this is obviously inconvenient at best. Additional symptoms when it doesn't start (these do not show up at all when it fires right up):
-voltmeter engages (i.e. comes up from its resting place with no key in the ignition), but reads no voltage
-fuel pump does not engage
-gas gauge does not engage (it has gas, I promise)
all lights, radio, a/c, etc. work fine

Also, while driving, the power frequently cuts out. This could be a separate problem, but it started happening at the same time as the starting issue. The engine does not die, but I lose all acceleration and the speedometer goes dead. This only lasts for a fraction of a second before power is restored, but then the engine also immediately downshifts for a few seconds.

First thing i tried, based on talking to a dealership, a different mechanic, and a few forums I found, was replacing the PCM. Bought a remanufactured unit, installed it, still having problems. Next, I actually took it to the dealer and let them diagnose it. They said the PCM was still bad, also recommended that i replace the CPS, TPS, TCM, and a solenoid (can't remember which, and can't find the paperwork at the moment) based on computer codes. Thats a lot of dough I didn't have at that instant. Went ahead and replaced the CPS, warrantied the PCM I bought, installed the new one, and prayed it would at least keep starting and i'd get to the other problems as the money came in. All problems completely fixed....for a week. Now, everything is back and I'm at a loss.

One more piece of info, no idea if its related, but seems to much to be coincidence. I have not had a problem getting it started in the early morning to go to work (about 6:30). Not once. Every time it wouldn't start it has been in the afternoon or evening, in the heat of the day. I mentioned before, it only occurred about once a week at first, and has been getting worse. Could be just a bad part/connection/etc getting worse, or if the heat is affecting it, getting later into summer and thus hotter.

I'm open to suggestions, and if i forgot any info just tell me what you need. Thanks in advance.

ZJMAX

Bad ignition switch causing factory security to act up maybe?

Max

b0dini

Interesting. This actually reminded me of one other thing. When it is not starting, if i turn the ignition to On, all the usual dings occur, then when those stop, the SKIS light comes on (it is also on while the ignition is turned to Start, but I can't remember if that's normal or not at the moment). It does this to both of my keys, so I'm assuming it is not a key problem. I had not considered the ignition switch not recognizing the key, but your suggestion combined with this makes sense. Further thoughts before I buy a new switch?

dave1123

Question. Do you use the tilt wheel function a lot? It could be a wiring problem in the switch wires under the column. Constant flexing can cause internal breaks in the wires themselves.

I don't use my tilt wheel at all, but I had to replace my clockspring at 158K. Always look for breakage in any wires that flex all the time, like doors and hatches. Copper is very flexible, but does have it's limits.

Just for ***** and giggles, try moving the tilt wheel up and down while it's running and see if it dies or stumbles.

b0dini

Ok, I was out of town this weekend, so I just got around to testing the tilt wheel. It just cranked on my lunch break (a "cool" 88 degrees outside here in arkansas, and i had to give it a little gas on the second crank to keep it from dying immediately), and it did not die/stumble after playing with the tilt function. If/when i get it back home (it was stranded at work this weekend), I'll go ahead and check the wires anyway. Planning on testing the ignition switch as well, fingers crossed it's a cheap fix.

To clarify the ignition switch, are we talking about the switch or the lock cylinder (which I have seen generally referred to as the ignition switch as well in a few places)?
Secondary question: if my problem is the ignition switch, i saw in a couple of places that it would need to be reprogrammed. Is this something I can do myself?

dave1123

The SKIS sensor is in the switch tumbler. It's a separate module from the switch itself.

b0dini

Ok, I've been out of town and am just getting back to my money sink. Is the SKIM something I can test myself with a scanner, multimeter, or something similar, or will this require a trip to the dealer? I'm trying not to go back there until i have to. They have not exactly inspired my confidence, assuring me they already had the problem fixed when they didnt, plus they left my TCM unplugged.

b0dini

Also, should the SKIM be faulty, I am guessing I would need new keys to go with the new module. Can anyone confirm, or will the new SKIM work with my old keys once it is programmed to my vehicle?