Codes, codes, and more codes

[Tooonz]

98 Tj, 2.5l project that was off the road for 9 years. I’ve cleaned every ground I could find. I’ve replaced the PCM with another used PCM. No change.
It’s like every day I spinthe wheel and see what codes come up. I’m getting a nice tan on the right side of my face from the Check engine light.

Just a short list of some codes…

P0463 Fule sensor A circuit High input
P0153 02 heater Circuit Bank1 Sensor 1
P0551 Power Steering Pressure sensor
P0138 02 circuit High voltage Bank 1 Sensor 2
P1391 Wheel speed sensor
And I know I had a crank sensor too ( which I’ve replaced )

Some days it runs good some days it sputters a little. I’ve been trying to just drive it and work the bugs out, however it’s weird How new sensors seem to be popping up and a common high voltage theme.

I’ve looked at the wiring harness too and haven’t seen anything obvious.

Any help would be appreciated, I don’t want to just throw parts at it unless I have to.

 

[Pascal25]

What kind of voltage do you measure when it's off, and when running? Does it fluctuate at all?
How do the wires and pins going into the PCM look?
Any noticed trends of behavior based on ambient temperature?

 

[Tooonz]

Pascal what would I measure when it’s off or running? The pins look fine for the PCM. I un taped those and did not see anything abnormal. As far as ambient temp. I have not seen anything different.

 

[Pascal25]

Engine off, battery should be a steady 12V or so.
Engine on, should be higher, around 14V, and probably moving around just a little bit, related to accessories (like A/C) and RPM Are the battery terminals nice and clean and a snug fit?

 

[Tooonz]

Engine off, battery should be a steady 12V or so.
Engine on, should be higher, around 14V, and probably moving around just a little bit, related to accessories (like A/C) and RPM Are the battery terminals nice and clean and a snug fit?

Yes terminals are clean and tight. I’ll check voltage this morning thank you.

 

[TJ Jim]

You didn’t mention fresh gas? Nine year old gas cannot be good.

 

[Tooonz]

You didn’t mention fresh gas? Nine year old gas cannot be good.

Hi Jim, Fresh gas yes.

 

[Chris]

98 Tj, 2.5l project that was off the road for 9 years. I’ve cleaned every ground I could find. I’ve replaced the PCM with another used PCM. No change.
It’s like every day I spinthe wheel and see what codes come up. I’m getting a nice tan on the right side of my face from the Check engine light.

Just a short list of some codes…

P0463 Fule sensor A circuit High input
P0153 02 heater Circuit Bank1 Sensor 1
P0551 Power Steering Pressure sensor
P0138 02 circuit High voltage Bank 1 Sensor 2
P1391 Wheel speed sensor
And I know I had a crank sensor too ( which I’ve replaced )

Some days it runs good some days it sputters a little. I’ve been trying to just drive it and work the bugs out, however it’s weird How new sensors seem to be popping up and a common high voltage theme.

I’ve looked at the wiring harness too and haven’t seen anything obvious.

Any help would be appreciated, I don’t want to just throw parts at it unless I have to.

Here are a few thoughts to help narrow down the issue:

1. **Ground Connections**: Even if you’ve cleaned every visible ground, sometimes a bad ground can be hidden away. Make sure the grounds on the engine block and body are solid. You could also consider running a dedicated ground wire from the battery to the engine or the chassis as a test.

2. **Wiring Inspection**: While you’ve looked over the wiring harness, it might be worth checking for any frays or breaks, especially on the harnesses related to the sensors throwing codes (O2 sensors, wheel speed sensor, etc.). Sometimes the issue can be in a spot that’s hard to see.

3. **Voltage Tests**: For the O2 sensors and the power steering pressure sensor, consider using a multimeter to check the voltage and resistance. If you're seeing high voltage where it shouldn’t be, it might indicate a short or an issue with the wiring leading to these sensors.

4. **Intermittent Connections**: Given that some days it runs well and others it doesn't, there might be a loose connection somewhere. Checking and reseating all related connectors could help eliminate potential intermittent contact issues.

5. **Possible Chafing**: Check for anywhere the wiring could be rubbing against metal parts, which could cause insulation wear, leading to shorts.

6. **Error Codes Reset**: After addressing any issues or replacing parts, make sure to reset the error codes and see if they reappear. Keeping an eye on which codes come back could help indicate where the problem lies.

 

[Tooonz]

Engine off, battery should be a steady 12V or so.
Engine on, should be higher, around 14V, and probably moving around just a little bit, related to accessories (like A/C) and RPM Are the battery terminals nice and clean and a snug fit?

Pascal I have 12v when off and 14 and change when running, looks normal.

 

[Tooonz]

Here are a few thoughts to help narrow down the issue:

1. **Ground Connections**: Even if you’ve cleaned every visible ground, sometimes a bad ground can be hidden away. Make sure the grounds on the engine block and body are solid. You could also consider running a dedicated ground wire from the battery to the engine or the chassis as a test.

2. **Wiring Inspection**: While you’ve looked over the wiring harness, it might be worth checking for any frays or breaks, especially on the harnesses related to the sensors throwing codes (O2 sensors, wheel speed sensor, etc.). Sometimes the issue can be in a spot that’s hard to see.

3. **Voltage Tests**: For the O2 sensors and the power steering pressure sensor, consider using a multimeter to check the voltage and resistance. If you're seeing high voltage where it shouldn’t be, it might indicate a short or an issue with the wiring leading to these sensors.

4. **Intermittent Connections**: Given that some days it runs well and others it doesn't, there might be a loose connection somewhere. Checking and reseating all related connectors could help eliminate potential intermittent contact issues.

5. **Possible Chafing**: Check for anywhere the wiring could be rubbing against metal parts, which could cause insulation wear, leading to shorts.

6. **Error Codes Reset**: After addressing any issues or replacing parts, make sure to reset the error codes and see if they reappear. Keeping an eye on which codes come back could help indicate where the problem lies.

I’m going to run through this list this morning. I did realize my third brake light was out, after investigating further I found one contact was missing from the body side, and it appeared the remaining contact was wired opposite to the tailgate. Meaning the top contact was the white wire from the body, which then connected to the top contact on the tailgate which was the black wire. I picked up another contact locally and switched connections at the body. Brake light works now and probably not related but now the light that illuminates the temp gauge works as well in the gauge cluster. Go figure

 

[sab]

…it appeared the remaining contact was wired opposite to the tailgate.

That would only matter if your third brake light was an LED. LED lights are polarity sensitive (the D in LED stands for diode, which is a device that blocks current flow in one direction). However, incandescent lights work with current flowing either direction.