Have you cleaned those grounds yet M?

 

No the jeep is at the shop getting a new computer but I doubt its gonna fix the issue.
Hopefully I will get the jeep back tonight fixed or not so I can get some item checked during the week end.

 

this is a 2004 WJ 4.0L correct?
your page reference 8-31-8 is for a 4.0L. I want to confirm eng.

yes "S" indicates a splice.
In manual go to 8W-70-1 it will help with S splice's, C connectors,

POST all codes - it is best to use a scanner esp as you have trans issues.

You think related to K4
K4 is a major ground, it seams everything runs there.
A weird question "Is your AIRBAG light on" ?
Lets try checking k4 for voltage - your TPS uses K4 its easy to get access at TPS. K4 is the Bk/LB wire.

 

POST all codes

I wish I got a nickel every time @jtec posts that. His truth would make me a rich man......

 

KEEP the old PCM ! !

AIRBAG light is off but it does te bulb check every start?

Delta0 the "K4" is the ID number of the circuit that is suspect. Its a sensor ground going back to the PCM.

KEEP the old PCM.

 

KEEP the old PCM ! !

AIRBAG light is off but it does te bulb check every start?

Delta0 the "K4" is the ID number of the circuit that is suspect. Its a sensor ground going back to the PCM.

KEEP the old PCM.

Thank you JT.
Where do K4s go to ground please?

 

A circuit simple Positive is voltage and Negative is ground. akin to a simple light bulb circuit.

measuring the circuit current the PCM will see if circuit is open.
Example SIMPLIFIED - PCM sends out 5v to temp sensor, thermistor changes current flow to ground. without ground the readiing would not change. And computer logic would go WTF and set a code.

 

Is that info for me please JT?

 

YES - Sorry I did not address it to you ....... I'm confused and dazed these days....
End of year insanity.

 

YES - Sorry I did not address it to you ....... I'm confused and dazed these days....
End of year insanity.

Thank you JT.

Have I got this right now please, in your example, K4 connects the sensor to ground?

Extending that then, every sensor has a K4 that completes the circuit to ground.

So there are lots of K4s, which go to ground near their sensor?
Rather than all K4s go to 1 ground point?

 

Well it seems like my limp mode was related to the PCM. Thanks for you're support guys, I learner a lot on my WJ but mostly learned about the Jeep community sticking together to get our truck back on the road , cheers !

 

K4 is a ground thru the PCM. it is a terminal at PCM the sensor wires splice and end at PCM terminal xyz.

sensors often have 3 wires.
the sensor has referance or feed voltage @5v
The sensor grounds back to PCM. the sensors splice together at S xyz S indicates SPLICE
Signal return or signal is the one the PCM uses to calculate.

 

K4 is a ground thru the PCM. it is a terminal at PCM the sensor wires splice and end at PCM terminal xyz.

sensors often have 3 wires.
the sensor has referance or feed voltage @5v
The sensor grounds back to PCM. the sensors splice together at S xyz S indicates SPLICE
Signal return or signal is the one the PCM uses to calculate.

Thank you JT.

 

For you're info I replaced the computer, had it flashed and problem solved !! Thanks for you're input guys !