Hello gents,

The truck is a 92 F-250 7.3L auto 4x4 287k. I tried to clean up my tach sensor this weekend to try and fix a jumpy tach issue I have been having lately. so I reomoved it carefully and cleaned it off with a clean rag , inspected the leads running to it, all looked good and it cleaned up pretty easy right. I reinstalled it and went about changing the oil.

So I changed the oil and started it up. well the trouble begins the moment I turned the key. the odometer flakes out and starts flashing a error 3 message every few seconds and the tripmeter resets itself. I thinking ok, I start it any way everything else looks good. the tach does not work at all now. so I thinking again great, the sugar to crap gods are smiling on me today. I take it out for a test drive transmission shifts like crap, real hard shift shock into second, won't go into overdrive at all. so I get it back to the house and call up my ford dealer to see if they have a tach sensor in. I am in luck. Murphy's law was taking a lunch break when I called and they have one in-stock and they don't close until 4pm on a saturday. I run down there in my other truck and pick it up , install it, and the transmission shifts like butter now, way better than before.

So, problem solved right, well almost. I did tell you the error 3 message in the digital odometer was still flashing right, right. even after replacing the tach sensor.

So I am on the way to the computer store today with kids in-tow, I am 5 miles away from the store and the overdrive light on the column shifter starts blinking. I was thinking to myself muphy was on vaction this past week thats why saturday when so easy, now he's going to get me good today. Transmission is really giving it to me, hard shift shock into 2 and overdrive gears. I limp into the store parking lot and pop the hood.

I figured this was the old OBD I ecu controlling the transmission, so maybe I will disconnect the batteries and dump the ecu's memory right. The OBD I ecu don't have any error correcting ability , so maybe it was holding on the tach sensor error from before. so I am in the store about an hour.

I reconnect everything and start her up , no blinking od light. however the error 3 message is still there. I drive back home about 35 miles and everthing is fine. no shift shock ,buttery smooth engagement. Does anyone know what this error 3 code is and how to get rid of it. I pretty sure if it stays around long enough the trans shifting problem will be back. thanks for any help on this issue.

V/R
John

 

John,

Did you replace the VSS sending unit in the rear axle. It controlls the speedometer and electronic tachometer.

Sure sounds like you finished off the Engine Tach Sender when you tried to clean it. (Don't worry it was gone anyways and as soon as you touched it probably shorted out completely)

It is time to get a code scanner OBD-I and read out your continuous memory codes. They will be stored in the tranny controller. This will help you shed some more light on the matter.

Note, although I had contray experience, most guys believe that all the continues codes get erased when you disconnect the batteries long enough. This is not a good way to erase codes. The best way is to use the code scanner procedure for deleting the code.

I have not bought one in ages but last I recall Wally Mart has OBD-I scanners for less than $30.

Here is another thing I recently came across, make sure your oil level in the tranny is up and the oil has been changed in the last 30k-50k.

If your oil level is two or three quarts low you could get codes 91 and 92 (First and Second shift errors) which would cause a blinking light and rough shifts.

Post your tranny codes once you have them. We got a long weekend comming up so I will be away from the computer a few days.

Note, all the sensors on the E4OD are a bit crappy and need changing every once in a while. (TSS, MLPS, VSS, FIPL) The MLPS was updated by Ford in 1995 and the new MLPS has a new electrical connector. It will take a bit of time to change the wiring over to the new connector.

Best of luck, I know how frustrating it can be I went thru it on my 91 F350 E4OD.

Seb.....

 

Hey Hamberger,

Thanks for the info, I bought a code reader last night and will check to see what codes come up. I will also check the fluid level. I checked it last week before towing my falcon wagon to its new owner.

do you think replacing the tach sensor helped finish off the VSS in the axle? the speedometer has never been jumpy or any other problems until I replaced the tach sensor.

Thanks for the help, will post the codes by this afternoon.

V/R
John

 

Alright here is the codes I pulled from the ecu

key on engine off
29 vss signal voltage too low

key on engine on
11 the system ok code

did I some how mess-up the vss by changing the tach sensor? Hamberger need some input on this. thanks for all the help.

V/R
John

 

Thanks John,


Just got back from our long weekend.

Code 29. I would change the VSS, less than $30.00 last I checked.

I don't think changing the Tach affected the VSS.

Both the TACH and VSS sensors are very prone to failure. You were just due on both of them.

Let me know if you still got problems after chaging the VSS.

PS use your code reader to reset you codes once the new VSS is in.


Good luck,

Seb.....

 

thanks man,


I will get the vss replaced this week. thanks again for the follow-up. Will post again once it is replaced.

V/R
John