P0740 error code possibly caused by wire harness shorting
 

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Wiring harness in question
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Harness is in the bottom right of this picture between air filter and radiator cap


Hi, I recently bought this 4.0L 01 grand Cherokee with 130k miles and the few problems I’ve had to fix were smooth sailing but I recently got hit with a p0740 check engine code. The night that I saw the code I had actually been burping a small bit of air from my radiator cap and some coolant got onto the wiring harness in question. I’m really hoping here that this is the cause of the open circuit and not a solenoid or the entire TCC itself. For the life of me I haven’t been able to figure out what the wire harness above is for nor do I have a multimeter to test it out with. Just curious if this harness is part of the TCC circuit or could in any way be causing the p0740 code. Thanks in advance

How is it running when idle and driving?

So far it’s running great. Idles around 600 rpm still with no roughness. When I’m driving the transmission changing gears is barely noticeable.

Help me out, what is po740 mean? Lockup solenoid? No multimeter, really? 5$ at harbor freight. Changing the solenoids is not a big deal at all on the AW4. Ebay has them 1/3 the cost of the stores...$90 for all 3. While you're at it you can change some fluid and the filter screen. she will thank you.

P0740 means the Torque Converter Clutch Circuit is open, I know the solenoids aren’t a big deal to change out and I’ve already changed the tranny fluid and filter but according to what I’ve read online a lot of times p0740 can be caused by a loose wire harness or shorted wiring. That’s why I was wondering about said wire harness pictured above. I’ll definitely have to get a multimeter asap. Thanks for the info on the solenoids on eBay, will definitely look into that if I need to change them out.

ok, maybe it's shorted, but what it's most likely saying is the solenoid is bad. By the time you get a meter and figure out which wires and how to test, you could have changed it. But, I'm all for diagnostics so if you are inclined or think that's the problem, by all means test it.

Thats true, I’ll probably just go ahead and do both then. Thanks

I could be thinking of the 42RE but isn't there 3 solenoids on the AW4? Yeah do it up. Just take your time with it, be careful and get them in there right and be sure you got it before you close it up. You'll be fine. It was well worth it when I did my xj.