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Discussion Starter · #1 ·
I'm about to part it out lol

It's bone stock with the 4.0 m/t and 147k miles. I traded a 4 wheeler for it in '03 and it's seen light off road but mainly driven around town. Last June it started smelling like it was running rich so I put a new O2 sensor, new plugs, wires, cap and rotor and it's been running fine until now.

The wife took it to work on a rainy day and when she tried to come home, it wouldn't start, just turn over. It had no fuel rail pressure and wouldn't start on ether.

Here's the symptoms:
- All gauges are dead, including *tach and speedo
- dash lights are dead
- check engine light doesn't come on
- parking brake light doesn't come on
- fuel pump is not coming on
- no spark

This is what is still working:
- head, tail and brake lights
- turn signals
- heater fan
- radio

Here's what I've checked so far:
- battery and cables good
- unplugged O2 sensor in case it shorted (heated 4 wire)
- cleaned all grounds under the hood, including the ones on the engine block behind the distributor
- cleaned up the fuse block in front of the battery, cycled out the relays
with the horn relay and tested
- checked continuity at the dash and elsewhere on the tub
- ECU has power going to it, then I swapped another ECU into it
- replaced ignition switch

I've been looking for the dashes ground point but haven't had any luck. Anyone have some suggestions?




* I know the speedo/tach are dead because while being towed, I had it in gear with the key on.
 

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I believe the fuel pump ground is on or near the parking brake assembly.

It's a place to start anyway...
 

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Sounds like the same issues I was having. I'm with timberwolf. Check all your grounds first.

Denis
 

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Discussion Starter · #4 ·
I pulled the drivers side firewall connection right behind the fuse box and cleaned some green out of it and had some short term success. The gauge cluster started working again and it started right up, but after idling for a few minutes it died.

The gauge cluster and all lights are working but as soon as I turn the key to the run position, the CEL starts throwing OBD1 codes and the fuel pump is not priming.


The codes are 12 and 33, both are expected so no hint there.
 

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If cleaning the connectors helped I would continue along that path. Once corroded, electrical contacts can burn thru the corrosion somewhat but if they arent perfectly clean it will always be a problem. Once you finish cleaning spread some dielectric grease on the terminals to help prevent more corrosion.
 

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Discussion Starter · #6 ·
I finally got it running this afternoon but I never did find the actual cause.

Pin #9 on the ECM was not getting 12+ from the ignition switch with the key on.
Pin #3 is the one with constant 12+.

I checked every connection for continuity and I decided I wasn't going to spend the time to chase down and inspect the wiring itself. Instead, I routed power from the ignition switch thru the firewall and into pin #9 at the ECM connector. I have a 5 amp in-line fuse where it's coming off of the ignition switch and that seems to be enough.

I even popped for a alldata subscription and that turned out to be a waste because I had already found the relevant charts and drawings with google.

I'm posting this follow up in case someone else has this same glitch and maybe they'll see this post before replacing the capacitors in the ECM :)
 
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