I have a 94 f150 with the 5.0 efi. The speedometer seems to go haywire anywhere between 35-60 mph then the tranny will shift hard up and down. Anybody have any clue what could be the problem, this dosnt happen all the time. Also it had a noise that sounded like a u joint in the front driveshaft after this happened, drove it like that for a bit and the noise is gone now??!?!

 

The engine and transmission are controlled by the same computer. The computer relies on accurate feedback for vehicle speed so your bouncing speedometer is another clue the issue is most likely based on a faulty vehicle speed input. Highly suggest you run the Key On Engine Off (KOEO) tests and CM code display.

Your truck could have either a 4R70W or an E4OD transmission in it. We need to know which one. Check the door jamb sticker for the transmission code while you are running the KOEO tests and stored code (Continuous Memory) display.

 

Thanks, I'll let you know as soon as I get off work around 7:30-8:00.

 

I believe transmission code U is a 4R70W. Trans. code E is an E40D.

Since the speedometer is acting up when the transmission is too I suspect you have an E4OD. Common causes of the combined issues are a faulty VSS (rare), faulty VSS wiring, faulty RABS control module, faulty PSOM (more common), wiring between PSOM and computer (PCM).

 

Your Right, It's it shows Transmission Code E on the door jam.

 

Your right, It shows Transmission Code E on the door jam.

 

When you run the codes I am sure you will find an error for vehicle speed input in the CM section of the stored codes.

The problem could be any of the items that Randy (rla2005) said above plus bad bearings or tone ring in the rear end.



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When I ran them before I beliee I got, low TP voltage and EGR valve not opening intermediately. This was before tts

 

Those codes sound like they are from the KOEO electrical test. The VSS codes do not show up in the KOEO electrical test. They are only displayed in the stored code (CM).
The CM display of codes are displayed after the KOEO electrical test are done and after a separation code of 1 (10 on a reader).



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ahh ok, I will have to try it out. Will they be 3 digit codes?

 

Yes they will be three digit codes.

 

alright, I'll let ya know what I get, thanks