Hello all! I own a 1997 F-150 Lariat that has roughly 286,000 miles on it. It still has the original trannie and engine (4.6 Triton) in it, neither of which have been rebuilt or needed significant maintenance. I take pretty good care of the truck, just like my Dad and my Grandpa did before me.

Just this week, it started giving me some trouble that is worrying me. My Overdrive light started flashing on the gear shifter. My first thought was that it was just bugging out on me, but then I felt the truck start to act up. After driving it for a few days to and from work (fifteen minute drive within the city), I was able to discern a few things:

1) It seems to be speed dependent, with the light beginning to flash at about 40 mph.

2) Before the light starts flashing, the transmission works okay. After the light starts flashing, it starts shifting rough.

3) It's hard to brake after the light starts flashing. Braking will slow me down like normal, but then it feels like the truck downshifts rough, making the whole vehicle lurch a bit. The weird thing is that it seems to take longer distances to brake when this happens. If I push the brake in farther, then it gets grabby.

This all started happening this week. Brakes are fairly new and everything (including the trannie) works great up until that light starts flashing. I'm taking it by Autozone tonight to have them read the computer and tell me what codes are registering. I'll post those up once I have them.

I'm hoping this is some kind of computer or sensor problem, but I'm worried that it may be the transmission. I've less than a year to go before I graduate college, so I'm hoping and praying that the truck will last that long without needing something major like an engine or transmission replacement.

Can anyone give me some advice on what might be going on with my truck, and what I can do to solve the problem? Many thanks!

 

Okay, to update this, it doesn't appear that the problem is related to speed. I put it through the paces on my way home this evening and it performed perfectly. However, after a while the light started flashing again and the truck started having problems again. At that time, I was parked when the light started. I'm thinking now that it's time-based.

I stopped by the local parts shop and had them check the computer codes. Only one is showing though, and it's the EGR code that's always on/triggered (design problem, not related to performance).

I'm stumped. Does anyone know of a fix for this?

Many thanks!

 

Take it to a transmission shop and have them read the codes, they have more high end scanners than the parts stores to read transmission codes. The flashing O/D light means you have a transmission code. Don't unhook the battery or it will erase it.

 

Thanks, I will do that!

 

Hello all! I am having some additional problems now that I am trying to troubleshoot. I'm hoping to get the truck up and running in time for the weekend so that I can travel home for Father's Day. Any advice would be greatly appreciated!

So, last week my truck transmission was very rough, shifting hard, clunking, and being generally unpleasant compared to its normally cheerful self. I scheduled a trip to the local tranny shop, but the day before I could go, I lost my instrumentation cluster including the Overdrive light that had been flashing. I thought it was just a blown fuse, but I replaced the fuse and it didn't fix the problem. Since losing the cluster, the tranny is working great again. I took it to the shop anyways, and the mechanic couldn't find anything wrong with the tranny, and suggested that it was an electrical or computer problem based on how the tranny started working about the same time that my instrumentation stopped working.

I checked all my fuses (none blown), replaced the cluster fuse despite it being good, checked all the dash plugs (none loose), and unhooked the battery for a bit to reset the computer. None of this solved the issue. I don't have the equipment to dig into the guts of my truck's wiring, so this will likely be a shop visit. Does anyone have suggestions on anything else I can try in the meantime? Maintenance is scheduled for this coming Wednesday, so if I can fix it before then, then I'll be one happy camper.

Many thanks!