I have a 1991 f350 2wd 7.3 diesel, it runs good and shifts through all gears good but i will not go into overdrive, is there something common that goes out in the transmission also how can i find out what trans is in there.

 

I'm assuming it is automatic. Does it have an overdrive button at the gear selector?

 

There were two automatics available for your truck in `91. One was the C6 which was a three speed auto with no overdrive, the other was the E4OD which has overdrive. There also was the ZF5 manual trans.

 

He probably has the E4OD since he says it doens't shift into overdrive anymore. He didn't say anything about a manual tranny.

 

no the o/d button is on the dash right below the gauges and yes it is automatic, if it is the e4OD (anyway to get numbers of the trans like and serial number or rpo code) is there any common problems and what do yall think could be the cause for it not shifting into o/d. thanks for the help

 

I am not too familiar with the E4OD since I have an AOD. It's all hydraulic no electronic stuff. So back to yours. Either the OD solenoid is not working or the transmission computer is not getting, or getting a bad signal from the Vehicle Speed Sensor. The transmission Control Unit does have diagnostics and will store trouble codes. Best thing to do is have the unit scanned and see what codes are stored. Also check your tranny fluid.
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we replaced the filter and fluid and where would i find the od solenoid and the diagonstic port to pull the codes or is there one?

 

ehh does your engine light come on at times? As I said I am not familiar with the e4od. Let an expert come by and tell you what's wrong. I wouldn't know where they would be located if they are even there. But they have to be there since it's electronic.

 

no no lights come on hopefully some one will chime in and thanks for the help

 

Hopefully you have the problem figured out by now but in case you don't i'd suggest the throttle pedal censor or something of the like. That'll cause the truck to never get to that last gear.