Archived Transmission Problem

[DennyDay]

I've got two codes in my system, 1st - PO500 - Speed sensor and 2nd,

P1765 - TRANS 12V SUPPLY RELAY CTRL CIRCUIT. This transmission is a Dave Goerend build with 5,000 miles on it. I've go a call into Dave, but if anybody has an Idea where this sensor and the relay are located and what should be checked, I would appreciate your help.



Denny

 

[JLandry]

The P0500 is usually associated with the rear wheel speed sensor, which is in the rear axle differential. It's a relatively inexpensive part and very easy to swap out.



John L.

 

[DennyDay]

Changed out the speed sensor on transmission, if the rear speed sensor is going bad won't that show an ABS problem?



Truck is acting funny - - running 40 to 50 mph, truck seems to stumble, RPM drops about 200, then picks right back up. Would a defective Crank position sensor cause this?



Denny

 

[JLandry]

Changed out the speed sensor on transmission, if the rear speed sensor is going bad won't that show an ABS problem?

Denny,



Not necessarily. Now I've personally never had the rear wheel speed sensor go bad on my truck so I'm not speaking from experience, but I've read several posts here where the only indication it's bad is the P0500 DTC or the speedometer begins acting strange. The rear wheel speed sensor is cheap and it can't hurt to swap it out. If it doesn't cure the problem, at least you'll have a spare.

Truck is acting funny - - running 40 to 50 mph, truck seems to stumble, RPM drops about 200, then picks right back up. Would a defective Crank position sensor cause this?

Hmmm... that's a tough call... it sounds like it could be a transmission related problem... maybe the torque converter locking and unlocking?



Since you got that P1765 DTC, I'd first try swapping out the Transmission Control Relay with another non-essential relay (such as the wiper relay) to see if that helps. It's located in the PDC (Power Distribution Center) on the driver's fender under the hood.



Good luck,



John L.

 

[DavidC]

When the rear sensor fails you will usually not have a speedo below 20 mph and a ABS light. If you have an ohmmeter you should read somewhere around 1800 ohms across the sensor (cheaper than the $50. 00) to replace what is not bad. I am not for sure but I think the trans speed sensor is a backup for the rear and that is why your speedo will work above 20 mph. The trans speed sensor will read about 600 ohms across the 2 pins if good.



Dave

 

[DavidC]

Missed one. The 200rpm sounds like the TC locking and unlocking, Could be associated with a speed sensor since the computers do not know your speed.

Could also be chafed wires from the frame to the rear axle as I have heard of this one.



Dave

 

[DennyDay]

David and John - - That makes sense - - the two sensors "not in agreement" kinda' what dave Goerend said also. The P 1765 code is caused by the removal of the relay and putting a lock-up switch in the truck. Hope the TC is not slipping - - its only got 5,000 miles on it.



Denny