Hello everybody. I have a 99 Dodge Ram 1500 4X4. I was going to work today the O/D off light comes on by itself. I have to drive up a long gravel road and have to lock it 4WD. When I turn the truck off and restart it the light goes off. I try to turn the overdrive back on when the light comes on but it will not go off. I had the tranny fluid and filter changed a month ago. This is the second time its happed in a month.
Does anybody have any ideas?

 

has it been very cold out? you overdrive should automaticly lock out if its below a certain temp.

 

Yes it has. It's been around 10 degrees with the wind chill below zero but it didn't come on till I just pulled in the parking lot at work which is about 50 miles from home. I thought it may be overheating but the transmissiontemp light doesn't come on and it shifts real good. When I had the fluid changed, he alsotightened the bands. The truck has 92,000 miles on it but it runs like a top. I work at a strip mine but I try to take it easy up the long roads as much as I can.

 

warm up your check book because tranny time is comin' My truck has had the exact same problems when the od was ready to puke. Tani1500 is absoultly correct with the od lockout in the cold but that isn't supposed to happed untill about -5 to -10 air temp. The trans temp light won't come on untill your trans temp is up to about 270-280F. to late by then.

 

I only drive it to work maybe 3 times a month, but 2 of the 3 times it came on. Does anybody no what type of transmission it is. The mechanic told me it was a 618 andcould somebody give me aestimated cost to rebuild it if needed.

 

Oh I forgot to tell that it has the 5.2L (318) and 3.92 gears 285/75 R16 tires.

 

That is how mine started. Then the check Engine light came on and set a code of P1740. I noticed that the converter stopped going in to lock up. I just had it rebuilt and I went buy to look at the hard parts. It was time. The band was just about gone. Lots of metal in the filter from the converter where it starts wearing the shaft then starts blowing by causing it not to go into lockup. $1986.00 later all is good. Mine is a 200 Ram 1500 4x4 5.9 with the 46 RE. They replaced converter, pump, band, seal, gaskets and plates. Selonoids were working fine.

 

You can mod the switch by groudning it out, so maybe somehow theres a short sending the ground single to the PCM. I dunno though. The switch is suppose to come on when the PCM gets the ground signal, not when the trans whats to stay out of OD