I have a 1992 F150, with a 300ci and automatic transmission, 2 wheel drive. This past week my "Low Range" light has been flashing on and off, and in the last couple of days, it is staying lit 90% of the time I'm driving. I notice when it's lit, the truck will bog down, and has no power to pass. What could be causing this? Is it time for a new transmission?

 

2 wheel drive and a "low range" light. I realize your truck uses the same dash as a 4 wheel drive truck and the low range light could come on but. Explain what the low range light is in your 2 wheel drive so we can figure out what is going on?

 

If you put a new transmission in it you'll still have the same problem. But at least you'll have a new transmission.

The problem is most likely in the wiring or the PCM. Both the wiring and the PCM are probably identical for the two wheel drive and the four wheel drive trucks. The difference is that the connection to the transfer case is left unplugged on the two wheel drive trucks. The wire going to the transfer case connector is probably damaged and getting grounded. The PCM thinks that this means the truck is in 4x4 low, so it turns on the LOW RANGE light.

It's also possible that the PCM is damaged and causing this.

 

Thank you. I will check all of the wiring going to and from the PCM. Since I made the original post, the "LOW RANGE" light stays lit all the time, and the truck will no longer kick down to low gear when I try to pass someone or speed up.