1999 F150 XLT 5.4L 4x4

My overdrive light on the end of the shifter is flashing. The truck still seems to go in and out of overdrive just fine and there are no idiot lights on. What is going on???

 

something has triggered a fault in the transmission, proceed to have the code retrieved and the transmission diagnosed

 

So i should go to like auto zone and have them hook up the scanner?

 

i dont know if their scanners will read the transmission or not but its worth a shot

 

no they wont, you need a Ford dealer for trannie problems

 

Not true, there are a lot of shops that have a capable scanner. However, Autozone scanners are not.

 

nope auto zone scanner blows haha. I tried and nothin came up. I went and stopped by my mechanic after work today and he has the super cool snap on scanner. Didn't get a chance to hook it up because it was late but ill go this weekend and see whats up. He seemed to be very familiar with this problem and narrowed it down quite a bit just by asking me questions. Like if the abs light came on ect.

I got on the freeway last night to mess with the overdrive and what its doing is when the overdrive is off or on it will go fine untill 3rd year and as soon as it goes into 4th the light starts flashing. I cant turn overdrive off and get it to stay in 3rd. It will automatically go into 4th and start flashing the light.

 

Mine will flash, but only when its above 75 outside, after the truck has been running for a while, and a couple other cariables. Its so weird. Keep us posted on what you come up with.

-Matt

 

If it flashes after OD engagment attempt, the convertor likely has a lock up issue.
The shifter switch signals on a pair of dedicated leads to the PCM to allow or inhibit OD.
If the PCM detects an issue, it flashes the lamp and may or may not allow OD engagment depending on what the problem is.
Everytime the ignition is switched off, this circuit resets even if the switch is in the OD off position (lamp lighted) when then motor was shut off.
Also an intemittant ground on the switch lead can flash the light but usually not on a regular basis. No light at all is a blown fuse.
A ground on the power side will blow a fuse. This fuse is also common to a few other functions you may see are not working at that time.
Tell us what was found.

 

Well my problem seemed to just go away. Everything works fine now. Only thing i did was i was getting on the gas a little more today then usualy.. ok maybe alot more haha. Just one of those days i gota open that big 5.4 up and have some fun but idk i might have just loosened something up and it fixed it. Can i still go and have the code pulled even if it stopped doing it?

 

Get that checked out ASAP man. Mine did this same thing and two days later i completely lost overdrive = rebuilt transmission. Mine was running fine too after it stopped, heard a grinding noise for about 30 seconds, went around and corner and went to accelerate and the engine just reved.

 

I want to go ahead and bring this thread from the dead.

I mentioned that my overdrive light flashes only after the truck has been running in over 75 degree weather for a while, but it doesnt always do it.

Is there a ground that could be loose? If so where is it located? Anything else I can check?


-Matt

 

If the OD light flashes, the FIRST thing you do is get the codes read.

 

Alright folks, got in to town today to see my transmission guy, and he ran the scanner on the truck. Pulled a 503 (Intermittent Speedometer issue) is what it said. He pulled the plug, cleaned it, replugged it, and cleared the computer of any logged errors for me. He told me to trace the wiring and see if there was a bare wire anywhere as well. Other than that he found no issues. Thank God!


-Matt