Just about over it....

[a-frame81]

So after spending $3k on the gearbox in the last 14 months I have been pretty happy to hang onto the Jeep since it had been working well again. Then in the last 3 weeks I've started getting a recurring P0430 code. It comes and goes, but hasn't affected how it is driving so I've been happy enough the clear the code and keep going.

Last weekend, we headed down the coast and it drove perfectly, albeit throwing the code once during the trip, but once cleared it didn't come back.

This weekend however....

We headed off to visit family in Dubbo and the run out was perfect. Just after Molong on the way back though, the ABS and Handbrake lights came on and the speedo stopped working. I tried to search for codes, but nothing came up on the scanner. We limped into Cowra making our best guesses on the speed we were travelling and I checked for codes again. No joy. I tried disconnecting the battery just in case, but no change. The speedo would come in and out at irregular intervals, but mostly we tried to follow other traffic all the way home, but about 45mins from home the MIL came on. There was no change in how it drove so I kept going, hoping to make it home. When we pulled in I scanned again:
P0430 - Catalyst system out of range (the usual one)
P0501 - Vehicle Speed Sensor A
P0573 - Brake switch A circuit high

Just about getting ready to sell it off for parts. What's going on with this thing???

[layback40]

I am new to KJ's but my experience with XJ diesels would make me suggest that you have a bad connection. One of the multi pin plugs is loosing connection on some pins. Some one who is more familiar with KJ's may be able to suggest what one.
What sort of scanner do you have? I am about to purchase one.
Good luck with your electrical gremlin.

[cmohr]

Hey Man, no good..

The speed sensor on the top of the diff is most likely the issue. If you have done any work in the back of the KJ it's possible to have bumped the wiring to it, a few folks have had an issue with the wires getting a little stretched making a loose connectiuon. I have had one fail and had both the ABS and speedo stop working.

The cat error is the same as my 1st KJ, a replaced the sensor a few times, even had it all checked by Jeep. They said it was working correctly, but the code was still there. It never interferred with driving.

I may have a spare Diff speed sensor laying around, I'll have to check.

[Methamon]

As CMOHR says Did mine a few years ago travelling to Coffs Harbour If i remember it cost be about 130 dollars for jeep to replace the sensor. These cherokee's are getting on in age and you need to be proactive in maintenance. When I see specials on i just purchase parts. Just did my crank and cam sensors and coils purchase from US Mopar parts total costed me $450 including postage. Last year was the injectors. Still cheaper then purchasing an new car and i hope i get another 5 years out of it.
I replaced my Cat sensors this year so i have the old ones if your interested

[a-frame81]

Thanks cmohr and Methamon, I'd be keen on any old sensors I can try to see if I can isolate the issue. Even if it means replacing them with new if they fix the issues.

I love the car, but it's causing no end of stress at the moment that as soon as I fix one thing another two pop up. I'm going to be replacing the rear UCA this week and still have to decide if I'll bother doing the AC compressor with everything else that is failing at the moment. I've been pretty proactive on getting things fixed/serviced since I've had it, but can't say whether that was the case with the previous owner.

[Billwill]

I agree that it is most likely the connector on the rear Diff sensor, the wiring going to the sensor or the sensor itself.

What year is your KJ?
There was a TSB issued years ago for all 2005 KJs whereby Jeep filled the rear Diffs with the wrong type of oil. This oil chewed up the sensor on the Diff. Fix was to take Jeep to Dealer where they then drained and cleaned the rear Diff, filled up with the correct oil and fitted a new sensor. I presume this also applies to Export KJs like we have!

The P0573 code could be the brake switch or connections to it....lets see if the problem remains!

The brake switch once removed cannot be used again.....big warning notice on it!
Have to fit a new one if this switch was removed so lets try to not go there!

[a-frame81]

Thanks Billwill for the advice. Won't go pulling the brake switch until I've tried the sensor.

If you don't have one cmohr, I just found some on ebay for about the $25 mark so they're not too bad.