edhunter

Looking for some information about what this code means. My truck is 2007 3500 with the 6speed auto, 4x4. I was checking the engine codes, and scanned the transmission while doing so. I got an error code PO935 which means "Hydraulic Pressure Sensor Circuit High" on the transmission scan. I cleared the code, started the engine, shut it down, and the code popped back up. The truck seems to run fine, but I have a 1000 mile tow coming up in a few weeks hauling a 40' GN trailer, and I'd rather not have any issues...
Any info appreciated, nothing showed up on a search...

edhunter

Worked on the truck a bit today, figured I'd change the fluid and filters since it's been a while since they were last done. Dropped the pan, changed the two filters, then pulled the transmission cooler return line. Put about 2 gallons of new fluid in the pan, put the truck in neutral, then started the engine. The return line was routed to a bucket. Cleared the codes on the transmission, started the engine, the code popped again, cleared and repeated. Any time the engine was started the code would recur, even with the pump line routed to the bucket with new fluid. I dont know much about these 6sp auto boxes, but I think it'd be hard to get a high pressure situation with the truck in neutral and the return line open. Thinking the sensor is bad?? Now to find it, decide if I want to replace it or not. Truck drives fine... If anyone knows if my logic is correct or not I'd appreciate the correction...

xcc_rider

From the diagnostics for the code:
The monitored Line Pressure Sensor voltage should always be between 0.35 and 4.75 volts. Any monitored volt- ages outside these parameters indicate an Line Pressure Sensor or wiring problem and will cause either DTC P0934 or P0935 to set.
• When Monitored:
Continuously with ignition on and engine running.
• Set Condition:
This DTC will set if the monitored Line Pressure Sensor voltage is greater than or equal to 4.75 volts for the period of 0.18 seconds
Possible Causes
(T38) LINE PRESSURE SENSOR SIGNAL CIRCUIT OPEN
(T160) SENSOR GROUND CIRCUIT OPEN
(T38) LINE PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE LINE PRESSURE SENSOR
POWERTRAIN CONTROL MODULE

So it can be the sensor, a bad ground connection at the sensor or pcm, a return signal short to power or a bad pcm.
The cheapest is to clean the contacts at the sensor and plug and see if it clears. If not then replace the sensor. Then its wiring time and you can pm me for a link to the trany diagnostics if you like.
From what I can make out on the diagrams the pressure sensor is on the passenger side near the rear of the trany.

edhunter

Appreciate the info but I think the trans may be f'ed... Changed the fluid, used the correct ATF+4. Drove the truck into work this am, a trip of about 15 miles. I noticed about 5 miles in that the truck seemed hesitant when accelerating away from a redlight. The trans shifted fine. Had to continue, had to get to work, but then the truck wouldn't shift out of 4th and the TC wouldn't lock up. Drove it easy until I got off the interstate, then pulled into a shopping center parking lot. Popped the hood, theres smoke coming out of the trans dipstick tube. Checked the fluid level, it's fine. Any ideas from someone knowledgeable about these transmissions? I just towed 1 week ago, a 400 mile trip pulling 15k lbs, and the truck did fine. I know I got the filters swapped correctly, not my first time doing the flush...
Feeling pretty screwed right now...
The truck has 210k on the odometer right now...

xcc_rider

Go ahead and pull all the codes. TransEngineer will need them to help diagnose the problem(s).

edhunter

Will do... when I checked the codes this am there were 3 of them, but didn't write them down. Will do and post 'em up... thanks!