Good point 
P0740 ****** code
- Thread starter HoosierJeeper
- Start date
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Side note: would my KJ have the 3 wire or 4 wire 42RLE?
mightybeet
Full Access Member
im in the same boat. p1776 still comes back after replacing solenoid, valvebody, TCM reflash and relearn. started slipping between gears 2, 3 and O/D with gear ratio errors and p1776. emailed sonnax and they said its one of the most difficult to diagnose. after searching around the interwebs i havent really found an answer.
- dealer cant figure it out. he test drove it heard it slip into neutral between 2 and 3, rev high and chunk into limp mode. dealer suggest replace transmission. $3000+ for reman.
- took it to a transmission shop and he heard the same thing and suggested rebuild since i already have a new valvebody from VBX with sonnax parts(all updated and such). either up to $2000 for rebuild or $3000+ for reman.
- dealer cant figure it out. he test drove it heard it slip into neutral between 2 and 3, rev high and chunk into limp mode. dealer suggest replace transmission. $3000+ for reman.
- took it to a transmission shop and he heard the same thing and suggested rebuild since i already have a new valvebody from VBX with sonnax parts(all updated and such). either up to $2000 for rebuild or $3000+ for reman.
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Bump for mightybeet. What did your shop find out yesterday? (I thought you took it in Thursday, maybe I'm wrong?)
mightybeet
Full Access Member
they had it all day yesterday and i havent heard from them yet.
Sounds like my story. Dealer had mine for 3 days last time before saying "We read that sometimes a bad TC can cause this, so we could just replace that for $2200 and see if that fixes it" Me: "But it drives normally so why would I do that?" Them: "We don't know what's wrong".
mightybeet
Full Access Member
when they tore out the transmission a few weeks ago it ended up being the TC. they replaced everything except the solenoid pack and valve body but called me after the install saying they needed to replace the pack because it was shifting slow. it could be the same issue with the new pack. found on another jeep forum(course cant find it now) stating packs were expiring with specific lot codes. some people went thru 2 or 3 before finding one that worked. so who knows how long its been on a shelf waiting for a forever home.
did they check the wiring from TCM to pack?
did they check the wiring from TCM to pack?
I'm not sure if they did. I would assume, but I'll try to find out.
My solenoid pack is new too. I wonder if it is defective? Mine shifts fine though. The pressure switch is in the solenoid pack, correct? I got my solenoid pack from someone on eBay.
My solenoid pack is new too. I wonder if it is defective? Mine shifts fine though. The pressure switch is in the solenoid pack, correct? I got my solenoid pack from someone on eBay.
mightybeet
Full Access Member
yes, the pressure switch is in the pack.
My dealer said that can cause a P0740, a bad pressure switch.
So are they putting a new pack in your KJ now?
So are they putting a new pack in your KJ now?
mightybeet
Full Access Member
they called later yesterday and said either pump or valvebody. doing pressure test monday.
Was the pump replaced?
How does yours drive?
How does yours drive?
mightybeet
Full Access Member
i guess they didnt replace the pump... but talk to sonnax they say pump, talked to shop they say valve body so gave them their contact info and let them figure it out.
Ok cool. Thanks for the updates.
mightybeet
Full Access Member
the sonnax guy was very helpful and listened to my ****** drama. based on his experience these types of codes can be linked to the pump size....hehe... he mentioned that up to a certain year they had a high volume pump but then offered a smaller low volume pump for better fuel efficiency. i guess a lot of rebuilders would install the smaller pump just to have to later install the larger pump once codes started to pop up. they talked and sonnax was willing to get me a new valvebody but with a wink and a smile.
uss2defiant
Full Access Member
did sonnax mentioned what year onwards did it go to the smaller flow rate?
mightybeet
Full Access Member
poorly paraphrased readers digest version:
early 41te/42rle had a crescent style pump with a tilted pocket. late models (2003 and on) have a dual cycloidal pump with a square/straight pocket to fix prime issues associated with the tilted pocket, better fuel, and less load on engine.
the dual cycloidal pump problems occur with normal wear and especially after torque convertor failure “may cause low volume when hot along with code P0740.”
early 41te/42rle had a crescent style pump with a tilted pocket. late models (2003 and on) have a dual cycloidal pump with a square/straight pocket to fix prime issues associated with the tilted pocket, better fuel, and less load on engine.
the dual cycloidal pump problems occur with normal wear and especially after torque convertor failure “may cause low volume when hot along with code P0740.”
How bad is it to replace the pump?
mightybeet
Full Access Member
probably a lot in labor cost but i would assume cheaper than rebuilding. its right behind the torque convertor.
Starting to think my pump is slowly giving out. If heat causes it to have low volume then that would explain why it takes a long time for the light to come on, only if it's on the highway for a few hours. Think it's worth putting in a new pump into a 150k 42RLE?
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