Hello to all the smart techies out there! I need some major help on my 1992 F250 7.5 4x4 supercab. The truck is in excellent running condition but the overdrive doesn't seem to work on my E4OD. The tranny shifts great from 1-2-3 gears but when I pushed the O/D on, the overdrive doesn't seem to kick in. Not only I'm running higher rpm on the freeway but I'm getting horrible gas mileage. The O/D light on the shifter is lid but no action!!! I took it to a local transmission shop where the tech ran an OBD test, I don't recall the exact code(s) but it's reported something about the torque converter is slipping, and a EGR valve issue - which is weird because the truck just passed smog here in California few days ago with no problem. So the tech drove the truck around the block and he felt no slippage and said the truck ran great except the O/D didn't work. There's just one thing tho, the odometer is currently indicating "error" instead of mileage...everything else on the speedometer, oil pressure, voltage works. Could this be a PSOM issue? He said the O/D is "gone"? and that I might need a rebuild - smells fishy??!! So I decided to post this hopefully some of you smart mechanics out here can help me out. Maybe something simple but just want to make sure I check out everything before a spending a fortune on a new tranny or rebuild! Thank you so much and God bless!

 

chances are it's not going to be a cheap,simple fix....but first,I'd drop the pan from the tranny,and look for evidence of metal.If you smell burnt fluid,and see metallic grey 'sludge' in the bottom of the pan and/or filter,you'll have more of an idea of what's happened.The torque converter is supposed to lock in OD to give you direct drive,so it may be the problem,but any metal contamination of you fluid ruins everything unless caught pronto.When did you last have the fluid changed?..

 

I believe we need to take a close look at something. And that is; when the OD button is depressed , it locks the trans in third keeping it from going into overdrive. Any other time the lite comes on, indicates a trans problem.
When the key is turned off the trans overdrive button is returned to the lite off position automatically allowing the trans to go into overdrive. You can get the vehicle going over 35-40 MPH and if you depress the OD button you should feel the trans downshift out of overdrive , and if you depress the button again you will feel it go into overdrive providing everything is working as it should. Could you have been driving it locked in third thinking it was on OD and that might be the cause for the poor mileage ?

 

If the lite on the shift selector stays lit on it's own, there may a trans problem requiring some further looking into. Is this what may be taking place at this time?

 

Trying to recall some info for you.
If the OD lite doesn't light at all any time , check the fuse panel under L/S dash . There should be a 10 amp fuse that feeds the OD lite circuit. Make sure that fuse is good.
It should be located adjacent to the flasher.

 

We've checked the tranny oil, it's semi-dark and smelled burnt. The OD light works as far as I can tell, it goes out and comes on when I pushed it, so it's safe to assume it's not the fuse problem. Could it be the fuild is so dirty it might have clogged the valve body? I drove on the freeway and hit the OD switch and it didn't go into overdrive.

 

On a 1992, 7.5 there are two fuses that are involved with the overdrive system.
As you stated the light is working so that eliminates the fuse for the indicator light. Now you need to eliminate the other fuse in the OD system. It is referred to as fuse #5. If you checked all the fuses involved which is the simplest and first step , then you can go on to more expensive and laborious stuff. The fact that the fluid has a burnt odor is not good and indicates overheating of the trans fluid . Unfortunately the best way to correct that is to remove and disassemble the trans. It would help if the cause for no OD was determined before disassembly, but that's not always possible.

Just to clarify,,,,the trans is supposed to go into overdrive when the OD light is off.

 

Thanks, I'll check on fuse#5 tomorrow and will let you know.

 

Checked fuse#5 it says unused. This is the fuse panel inside the truck. There's another power fuse panel in the engine bay, checked no blown fuse. Where should I look next?

 

Put a 20 amp fuse in there and see what happens.