Greetings,

I have a '99 F250 SuperDuty Diesel with an Automatic Transmision. There is a button on the end of the gear shift which allows you to turn off overdrive -- in other words the transmission won't shift into overdrive once you press the button.

Here's my problem. I start off driving normally. I've not done nothing to the overdrive button and the truck shifts normally into overdrive. 10-15 minutes down the road, the overdrive light (which indicates the state of the overdrive button) is FLASHING. Pressing the button doesn't stop the flashing. Once this flashing starts, the only thing I notice is a much more abrupt shift from 1 -> 2 gear. Odd.

Anyone have any experience or advice?

Regards,
kc

 

I don't know what the resolution was, but I've heard of this symptom before.. Your ford dealer probably knows how to fix it.. I would assume theres a TSB on it.

 

The blinking light means the computer for the tranny senses a problem. Have the dealer look at it asap.

 

 

2002 7.3 PSD with blinking O/D light = $4100 new tranny

 

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I had the same problem with my 05 F 250 that started about 50 miles after I picked it up.

Was told it was a "shifting solonoid " inside the tranny. They had to drop the pan to get to it, but it was a simple fix.

It was covered under warranty so I can't tell you what it would have cost.

 

my old 99 done the same thing and the sensor on top of the rear end had gone bad. it's easy to find it's right on top of the rear chunk, you have to take it out to add rear end dope, it has a magnet on the end to catch metal fragments. i know this sounds confusing but get under your truck and you'll see what i'm talking about. i think the sensor is only about 20 bucks from powerstrokeshop.com. PM me if you still can't find the sensor.

 

The only way to know what's going on is have the code read. When the OD light flashes an error code is stored in the computer's memory. A Ford specific scan tool is needed. The auto parts stores that say they will read codes free usually can't read a transmission code.

 

you need to find some one with a shop type scaner to read the trans codes. thats the starting point. not running and getting a trans rebuild . the other guys have said as it should be started every time. read the codes first.

 

did you find the issue to your overdrive problem? I am having the exact same issue with my '98 ranger. drives fine until I hit about 50-60 mph then o/d shuts off and shifts very hard when I slow down. The shift button does nothing at this point. I have changed atf, oil, filters, plugs and wires, etc to no avail....I am leaning towards the speed sensor but wondered if you got your issue resolved.

 

If your transmission is shifting hard and the lights are flashing, you're driving a ticking timebomb. The more you drive, the more damage. Take it to a dealer.

 

Probably a bad VSS sensor at top of the differential....but as others have said, don't throw parts at the problem, have the codes read and fix it the first time.

 

I had same problem with F350. Tried new VSS and cleaned MAF but still blinked. New transmission - quit blinking. It wouldn't throw any codes.

 

Sure it did. You must not have had the right scan tool to be able to read Ford transmission codes.