TJ won't start

DennisWuest

DennisWuest

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Supporting Member
Joined
Apr 13, 2023
Messages
13
Location
Lindale, Texas
2005 TJ, 4.0
I replaced the starter. Had the battery tested. Good. Cleaned the grounds. Ran a direct negative cable to the block. Ran a direct positive cable to the starter. Put on brass post connectors. Starts sometimes. Single click other times. Out of ideas.
 
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Okay. It will start and run all day turning it on and off. But then, out of nowhere, it won't start. The P codes are saying all four oxygen sensors are out. Will that keep it from starting, though? I know my gas mileage has got so bad I checked underneath for a gas leak. I just had the fuel pump replaced last year.
 
O2 sensors won't cause a no start condition... unless perhaps they were so damaged that the power circuit was being shorted to ground.

You might have plugged cats.

-Mac
 
OP--The O2 circuit is shared with a few other important things and a short can definitely cause a no start issue. I think it triggers the ASD relay.
 
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DennisWuest said:
Okay. It will start and run all day turning it on and off. But then, out of nowhere, it won't start. The P codes are saying all four oxygen sensors are out. Will that keep it from starting, though? I know my gas mileage has got so bad I checked underneath for a gas leak. I just had the fuel pump replaced last year.
Click to expand...

Codes for all 4 O2s on a 2005 or 2006 is a sign of the PCM going. Only known solution for these junk PCMs is @Wranglerfix . This may or may not be related to the no start. Mine would just shut off driving down the road, but with my MT, it would restart while still moving. Gauges would drop out when this happened as well.

Have you tried starting it in N instead of park? Could be a bad neutral safety switch. Try starting in N and moving the shifter around.
 
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Thanks for replying. But I may have fixed it. Until it won't start. But it's starting strong for now. I hooked a positive cable directly from the battery to the starter and it's working. Maybe you can tell me it that's safe. I left the old positive cable on to go to the fuse box and alternator and wherever.
 
As in a large gauge cable on the large lug for the starter?

Or a small gauge cable to engage the solenoid and essentially hot wire the Jeep?

The only argument to working is an electrical fire...

-Mac
 
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A four gauge wire (thick) from the battery post directly to the starter. It's been three days and starting perfect with no apparent problem.
 
JKP said:
Codes for all 4 O2s on a 2005 or 2006 is a sign of the PCM going. Only known solution for these junk PCMs is @Wranglerfix . This may or may not be related to the no start. Mine would just shut off driving down the road, but with my MT, it would restart while still moving. Gauges would drop out when this happened as well.

Have you tried starting it in N instead of park? Could be a bad neutral safety switch. Try starting in N and moving the shifter around.
Click to expand...
 
There is. I left it because it was a harness going to the fuse box, also. I just put an extra one on. The link going to the starter must have been bad. I replaced the ground going to the block, too, for good measure. And cleaned those other wires on the block and firewall. I had to buy an exterior star socket. I never heard of one. The grounds weren't the problem but at least they're done.
 
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