E4OD only has 2&4 if you shift manually

[brdmh44]

Hi guy's, I'm hoping someone may be able to help me with a truck that doesn't want to shift.

If you place the shifter in OD it will take off in fourth gear, if you place it in (1) it will take off in (2) and stay in (2) unless you manually upshift the trans.

Also, the overdrive light will not glow.

This leads me to believe the trans is not getting power or perhaps the wrong relay is installed.

If someone with a 7.3 IDI E4OD combo could give me the OEM part number for the transmission relay I would appreciate it greatly.

I have tried changing the computer and no luck.

The tachometer also doesn't work.

Any help would be great.

THANKS!

 

[J D Recovery]

Not to sure but I think the trans needs the input from the tach sensor to shift. Try changing the sensor in the top of the idi cover. Again not sure kinda new to desiel hope someone will let me know if I'm right.

 

[Goofyexponent]

The light on the shifter does not work at all?

If the trans starts off in 2nd gear, it's in limp mode. Scan it and see what codes it is throwing!

 

[NJKen]

If you have no tach the computer does not know what to do. The first thing you need to do is get that fixed. tachs sensor failure is fairly common.
Ken

 

[sootman73]

also take apart all the wiring connections and use electronics cleaner and dielectric grease on them. it doesn't sound like much but it really makes a difference. yea the computers never go bad on these trucks. which is why they dont make them.... where did you find one?

hook your old computer up and run with that. i dont know of a relay for the trans... its not that simple... my biggest thing would be the connector to the solenoid pack(on the passenger side) or your solenoid pack has gone bad. much more common thing to happen. its not in limp mode its just in the default setting. in D ur starting out in third. when you go to 1 or 2 its in second. i've been here multiple times before....

def scan for codes. autozone or the like will be of no help for this. their little pea shooter scanners can not read what a real mechanics scanner/computer will be able to tell you. and the diagnostic port for the trans is under the hood on the drivers side fender by the hinge/spring.

 

[david85]

Guys hang on a minute.

The tach and speedo signals go through the PCM before they reach the cluster display so not having a working tach in this case doesn't mean the tach or RPM sensor are bad. Same goes for the speedometer. I don't think he should be replacing ANYTHING until he finds out why the computer isn't getting power. That alone can and will cause all of the above stated symptoms.

No power to the TECA also means that codes can't be retrieved.

Find the transmission relay and verify that its getting power with the key on. If not, try Temporarily to splice power across to see if that works. We had some one on FTE with a very similar problem recently and he traced it to the ignition wire that is normally supposed to supply power to the TECA* relay.

(*TECA = Transmission Electronic Control Assembly)

 

[brdmh44]

Hi guy's,

Thanks for the replies.

I'm pretty sure the problem is the TECA circuit not receiving power.......but I cannot find a good wiring diagram or the OEM part number for the relay. I have a friend with the snap on scanner(s) for transmissions and he was ubable to pull codes since there isn't power reaching points it should be going to.

From what I have gathered is the TECA is a two part circuit. 1 part diode 1 part relay.

This is where the confusion sets in -- Where do I check for power at, and where should it be coming from.

The book shows that gas and diesel trucks use a different relay circuit for the transmission... the relay in the diesel truck is the same as in the gas truck.

So my question is can anyone with a 92-94 (NBS) or another 7.3 IDI NON TURBO truck please get me the part number of the TECA relay? If your facing the front of the truck and have the power center cover off... it's the relay located closest to the right of the left fender. (standing in front of the grill)

Thanks guys for the replies... I cannot wait to drive the truck with 1 and 4..!

 

[LCAM-01XA]

Guys hang on a minute.

The tach and speedo signals go through the PCM before they reach the cluster display so not having a working tach in this case doesn't mean the tach or RPM sensor are bad. Same goes for the speedometer. I don't think he should be replacing ANYTHING until he finds out why the computer isn't getting power. That alone can and will cause all of the above stated symptoms.

I thought that's the case, but with the PSOM, not the PCM/TECA - it's the PSOM that controls the cluster on the '92-'96 trucks, and it also feeds signal to the PCM/TECA - inop PSOM results in a very confused PCM/TECA and also no gauges. But if the speedometer is working then the PSOM is good, so the problem with no tach is likely the sender on the IP gear cover...

This is where the confusion sets in -- Where do I check for power at, and where should it be coming from.

The book shows that gas and diesel trucks use a different relay circuit for the transmission... the relay in the diesel truck is the same as in the gas truck.

So my question is can anyone with a 92-94 (NBS) or another 7.3 IDI NON TURBO truck please get me the part number of the TECA relay? If your facing the front of the truck and have the power center cover off... it's the relay located closest to the right of the left fender. (standing in front of the grill)

Since you know which relay is the TECA one, how about some circuit diagnostics with a test light? Pull the relay out, and test all of its four spade connectors in the distribution center for voltage:

1) with ignition off one of the four should have battery voltage, and the others should be dead.
2) with the ignition in the"run" position (no need to start the engine) that same connector should stll have thebattery voltage, but now one of the other three connectors should have voltage as well - this new one is the relay trigger.

If this is the situation you see then pull the A/C relay or running lights relay (if anyof them are present on your truck, they may not be) and plug them in place of the TECA relay and see if it fixes the issue, if it does then you need a new TECA relay which should be obtainable at about any parts store for around $10.