Cummins Diesel Forum banner

no 4th or overdrive does lock up i searched

2K views 10 replies 4 participants last post by  alwaysfaded 
#1 ·
ok so 96 2500 4x4 47re auto
tps is good and has been modded to a potohmeter
also have a lock up switch
all guages work except my coolant(was told this only controls gauge does not go to pcm is that true)
cruise control works
speed works
i put it on a scanner no codes but says my engine coolant is at -40deg hence no gauge working

so driving the truck tranny shifts normal 1-2-3 then lock up never even tries to shift to 4th tranny does not slip fluid is clean and fresh the dash button works but only unlocks the converter for a few seconds then locks back to 3rd tells me it works
lock up switch with od on or off works but only locks 3rd
i searched alot and came up with
it could be coolant temp sensor
tranny temp sensor but its in the trans
a little black box on front of the block i think its the ess
or the od solonoid itself ( this is what i suspect)
so how can i figure out what it is without buying all new sensors
any help is greatly appreciated
thank you
 
See less See more
#2 ·
I would try to fix the coolant gauge. It could be the wire has come off the sending unit on the very back driver's side of the head. Next would be a pressure check of the OD in the trans. It could be the clutches are shot and simply not working. You can get a factory service manual and find the exact wire going to trans for OD lockup and ground it out at the correct time to check for OD engagement also. If lockup works correctly, then that rules out ESS (Engine Speed Sensor) by harmonic balancer. It could be the OD switch on dash, but your description sounds like it is working, just not OD not working period. It could be wiring issue going to trans, terminal connection on trans, solenoid in trans or worse case, OD shot.
 
#3 ·
i ordered a new coolant temp sensor the wire was hooked up just sensor shot
od worked flawless before just all the sudden wont work i hope the od is not shot
 
#4 ·
john deere hy gaurd or case hystat fixes everything I have 674000 and my tranny has never been apart or any problems I have used hy gaurd since about 100000 tranny shifts like new, A bud of mines tranny would not go into od tranny shop said od clutches were shot, put hy gaurd into it he has now driven 65000 no problems . hygaurd will grab even if there is no clutch material left.
 
#7 · (Edited)
it should tell you od solenoid on/off or yes/no
i know a snap on one does, an otc, and a mastertech will because ive used all three... hmm maybe try again, look in sensor solenoid tests to check it manually. I had a bad tc sol and the computer would say tcc sol ON but it would unlock and lock whenever it pleased..

just out of curiosity are you using a pocket scanner or a diagnostic scan tool like a shop would have
 
#8 ·
its a matco for a shop my buddy is master mechanic so its a good one but im thinking i should take this sucker to dodge to see what there computer will say
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top