Dodge Cummins Diesel Forum banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!

1 - 3 of 3 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
So ill make this as short as possible. I do alot of hot tech diags on electrical for other shops. I am very familiar with od and converter drop out on 24v trucks. This one kicked my butt for a couple hours so will share the frustration haha.

2003 3500 ctd 48re. Rebuilt transmission about 2 years ago and came to shop because kept dropping cruise control and very intermittently downshift to 3rd . Went to typical rf or dirty voltage tests. Had no ac ripple another shop installed noise filter many years ago on apps wire and bypassed ecm to pcm and tapped apps sensor directly to pin 23. Had no connector corrosion and recall was done with orings and dielectric many years ago. So after ripple test hooked up scanner and scope and went after fan clutch..wasnt the problem. Took truck home one night on 30 mile drive and cruise would drop out 3 or 4 times then be ok for few miles and resart process and eventually drop od. On scanner could see everytime cruise dropped the tcc solenoid was commanded off for a split second. Couldn't even feel it. Just dropped cruise. After checking over wires and doing wiggle test with scope hooked up I actually hooked up both my scopes and borrowed one to watch 9 channels. What I wound up seeing is 5v reference drop down to 3v on about 5 sensors. At first thought pcm regulators... but couldn't prove it. So wound up isolating sensors until 5v drop and + stopped happening. It wound up being trs sensor. No oil coming out of pigtail but problem definatly went away. Changes trs and all repaired... drilled a hole in sensor and sure as hell was filled with atf. So was shorting 5v reference to ground and at least 3 times had 9v show up because the 12v keyed input transfered over to 5v section.


Never seen this problem before and have no oil come out of connector when unplugged. Trs did have slight amount of oil where aluminum is crimped onto plastic.


Guess I always assumed it was more of a neutral safety with contacts and the digital components within for mlps just never clicked. Gotta love the digital age..lol.
 

·
Trying to learn
Joined
·
7,909 Posts
924346

Nice find, hope this is able to help others
 
1 - 3 of 3 Posts
Top