Intermittent no-start

[WAM]

Seems to be associated with the gauge cluster or maybe it's connectors.

Rumor has it there's an old TSB on wiring or connector problems under the dash. Anyone know anything?

This on a 2005 Rubicon TJ.

[brokenujoint]

I can tell you this. And it may be a long shot but, when's the last time you replaced your battery? I had my tj giving me intermittent starts. It wasn't a typical dying/dead battery symptom either. It either fully cranked and started or it was simply dead in the water. Tested the battery and it was good. Tested it a few days later and it was toast.... If it's been more than 5 or 6 yrs I'd look into that.

[6spdYJ]

First, is it no fire or no cranking? Each has it's own list of probabilities.

[WAM]

No cranking, push-start won't work, gauges dead. Headlites work but don't dim when attempting to start.

I found the TSB -- not applicable.

I'm assessing it as either a gauge cluster problem or the wiring/connectors leading to. (Because a sharp rap to the gage cluster area gets the gauges working. If they work, the Jeep starts)

Rumor has it the Jeep will run with the GC disconnected. That's my Plan B if I get stuck again in the outback.

[6spdYJ]

No push start indicates no power to the emergency shutdown relay. We need to find the link between the ignition switch and the ECU. IIRC the 2005 specifically had an issue with everything being run through the multi-function switch. I'll see what I can find in my manual.

[WAM]

Multi function switch: = Headlights/turn signals? Would it be useful to do an inline disconnect of that switch at a time the dash is dead and check for voltages on any of those pins? I do know the headlights would turn on, so the MFS has to have some power running thru it. I don't remember checking if the turn signals worked.

[6spdYJ]

The "Daytime Running Lamp Module" has a fused ignition switch output to the start and run circuits. I'd start with locating this dude. Once you can replicate the no-start, tap directly on this component. Make sure it's not so hard that you shake the dash, you just want to isolate the vibration here to see if it reliably allows a start.
FWIW, [COLOR="#FF0000"]The headlight dimmer output is run through this thing too.[/COLOR]

[WAM]

My 05 Wrangler FSM says DRL are on Canadian models only. If I had a module it appears it should be high on the cowl/firewall just above the fuel rail. If I'm looking at the right place on my Jeep, there's nothing there. Am I missing something?

[Navy-Jeepster]

Do you have an air bag light on also?

When mine was a no crank issue, it was blowing the starter fuse.
It would push start though.
Find a factory service manual with the wiring diagram to help trace out the wires.

Todd

[6spdYJ]

I see the Canadian thing. It was on a different page from where I was looking. It sounds like the automatic shutdown relay isn't firing occasionally. The ASD relay is located in the Power Distribution Center, but it gets it's ground through the ECU. I'd be looking for a loose ground connection at the ECU. Isn't that on the firewall opposite the gauge cluster?
A few more questions: Does it only do this after being driven or can you start it, turn it off and not start (without driving)? Does it only do it at certain temperatures such as warm or cold?

[WAM]

All the relays have been swapped around with identical non critical relays like from the horn etc. Plus I replaced a couple just on spec.
On a possibly unconnected issue, the dealership put a new computer in to address some O2 sensor circuits. Would any ECU grounding issues have been reworked at that point? This was done after the on-set of the no-start problem, but the problem seemed unaffected by the new computer.

Since it's started acting up, it's had hundreds of start opportunities to screw up in street use. Only once has it gone into no-start, and that after sitting unused for a couple weeks. By contrast I'm getting multiple no-starts with every offroad trip. I have to attribute that to vibration. I've seen no pattern on temperature. It can no-start first time in the morning, or after a 2 minute view break on the trail.

Most of these problems have occurred far from pavement, so you can understand that once I manage to get it started out on the trail, I'm not often inclined to shut it off and try again. My buddies would just leave me there for being that stupid. But I think, yes, I can rap on the dash to get it to start, then shut it off and it will start again. For now.

I see the Canadian thing. It was on a different page from where I was looking. It sounds like the automatic shutdown relay isn't firing occasionally. The ASD relay is located in the Power Distribution Center, but it gets it's ground through the ECU. I'd be looking for a loose ground connection at the ECU. Isn't that on the firewall opposite the gauge cluster?
A few more questions: Does it only do this after being driven or can you start it, turn it off and not start (without driving)? Does it only do it at certain temperatures such as warm or cold?

[Elusive]

is it an automatic?
jeeps have been known to have bad safety start switches. try cleaning the contacts for the switch in the shifter. or at least crank it in and out of park a couple times when it does it.

[WAM]

Nope. 6-spd. And I permanently shorted the safety switch wiring during the troubleshooting. Which eliminates it as a suspect.

Another no-start today in the WalMart parking lot. Gauges came alive with the first fairly gentle rap to the dash, right of the steering column. It's getting more frequent though.

[6spdYJ]

Did it do this before the ECU swap?

[WAM]

Yes, the no-start problem cropped up before the ECU replacement. Which was done to address some codes. The no-start continued to be a problem after the ECU swap, but the codes are gone. Seemed like the no-start and ECU issue were unrelated.