O/D Switch

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About twice per YEAR, my overdrive switch magically turns itself off. This has happened since the beginning when I purchased the truck new (1994), and can be particularly disconcerting when traveling at interstate speeds. The rev limiter prevents damage (I assume).

At 80,00 I had a new transmission installed when the original blew (REAL interesting story). Didn’t solve the problem. I had the O/D switch replaced with no results. I guess the problem is in the electrical interface of the O/D switch with something else (PCM?). Anyway, would like to solve, though it’s more a nuisance than a real problem.

 

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Could it be the temp sender is acting up?OD is programed to shut down when the fuild temp is below 60 or above 270. I'll bet you have an intermitent bad electrical connection.

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95' 25004X4,AT,Driftwood,Banks,Warn fender flairs and running boards(Play truck)95 3500,5 speed,driftwood,Banks&phscotty,34,000 GVW apple and tractor hauler(work truck)

 

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Tuffcat,

This is one of those "who knows" kind of things. Mine has been doing it since it was new and I haven't been able to figure it out or find anyone who can. My transmission temp sender has been replaced and the symptoms are the same. Every few months or so it does it. If you find a fix PLEASE post it.

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Joe George
Eureka, CA

'95 2500 CC auto 4X4,3. 54,Combo EGT/boost guage,custom switch panel,PacBrake,TST #5,BD valve body,Automatic motorhome steps on both sides,Foldacover hard bed cover,Cummins chrome kit,Black steel grill guard,Front hitch receiver

 

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Mine has done that twice, both under different operating conditions. I made some notes in my "maintenance diary" and went on down the road. Both times (@ around 68K and again @ about 85K, I think) I just pushed in the switch to reset O/D and that was that. I do agree that it's probably something electrical. A small nuisance, but nothing more.

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95 2500 SLT, clubcab, 2wd, longbed, a/t, 3. 54, 131K miles, "all the usual refinements"

 

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Ditto with me. I bought mine used but have had the problem periodically. I agree that it is probably some sort of electrical thing. I can't replicate the event, it just happens when it wants. Not sure why. Just hit the O/D switch again and drive on.

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94 2500, AT, 4x2, 80,000 miles

 

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I have had a '94 gas and my '94 Cummins both do it. Intermittantly, always with the cruise on. (You loose your cruise setting too).

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'94 3500 4x4, 196,000 miles, Auto w/shift kit,3. 54 Gears, TST #5 plate, 235-85-16s, Rancho 9000s w/remote, Isspro gauges inplace of cupholder & Amsoil Bumper to Bumper. NRA member.

 

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Glad I'm not the only one. The first time it happened, I was really like #ad
WHAT'S WRONG WITH THIS THING?

 

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Judging by the number of replies, there are probably a lot more members who have experienced the same problem. Evidence from forum replies suggests a design flaw somewhere in the electronics. Too hard to run down (though I will have a bout with the schematics this weekend). Maybe one of the engineers who designed the system will see these posts and help us. "Fortunate1" is correct in that the problem is only a minor nuisance. But TD lovers don’t like to live with even minor nuisances with their “babies. ”

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94 Ram 2500 automatic. Banks Git Kit and air filter. Lock-out switch. Lost cat. 165,000 and Truckin!

 

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Mine has done it also, just last week when i was starting out for a six hour drive, 20 min from home in a rain storm, cruise set at 60 mph and it dropped out of OD, and cruise. i thought the transmission was losing fluid( plastic connector) but could not find any problem. reset od button, have not had problem since??

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95-2500-ExtCab-LB-4x4-Auto-AMSoil Air Filter, Bypass Oil Filter by others, AMSOIL and Mobil Synthetics, TST 255HP and TransGO Shift kit .

 

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Me too. Me too. Twice a year! Dealer replaced a bunch of stuff while under warranty but only managed to screw up the transmission select lever adjustment. My guess is that this is a EMF buildup problem and DC does not have a clue! To many damn wires running around on these diesels. #ad


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1995 2500 SLT Club 4x4, auto, 3. 54, 3300 pound Elkhorn slide in camper, AirLift air springs, Ricka dual wheel adapters, K&N, DC tow hooks, Rancho RS9000, Hellwig rear sway bar.
101,000 miles and counting.

 

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I've had this same problem with mine since day one and have no idea as to why it happens. If a solution is found please post it so we can have another small problem out of the way.

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94 4x4 SLT Geno's guages,TST 230/605,straight pipe from turbo,115,000 miles, horton fan clutch,RS9000 shocks, BD torque converter,valve body and pressure lock,Scotty air

 

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Lost my O/D, tac,alternator, then all would come back. An obvious electrical problem. After much hassel I finally got to an electrical shop that allowed me to come in when the intermit condition would appear. The electrical would act up when ever it wanted even with different loading. After about an hour with the wizzard checking the broken system, he called me to the shop floor and showed me what it was. He applied preasure with his hand to the computer plactic housing mounted behind the turbo and each time he hit it a reaction of everything working and then not working. A broken or hair line crack in the computer board was the problem. The wizzard told me that if he were to build a truck ram tuff he would put it inside the cab and not on the fire wall because of the obvious exposure to the heat and outside elements. I have had the same type of screwee stuff happen with my 4th rv frig and my 5th rv heater. Good luck I spent about $450. for the reconditioned circuit board on my won ton dually. Stephen in Sanger CA.

 

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Thanks to all TDR members who gave input on this problem. I suspect that Stephen in Sanger has nailed it. We know from the input that the problem is not associated with ANYTHING in the transmission (unless there is a design flaw somewhere, and in that case it would be futile to replace any parts with original equipment) I had my transmission replaced with no change in the problem. The problem is not in the switch—I had it replaced.
I am now wondering if the PCM is not the cause of other intermittent problems that I have blamed on (e. g. ) the TPS design!

Great Labor Day to all…


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94 Ram 2500 automatic. Banks Git Kit and air filter. Lock-out switch. Lost cat. 165,000 and Truckin!

 

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WOW, what a detective!-- my 98. 4 hasn't had that, or really any, (aside from the "OH,(^%T!!" scare w/my oil pressure guage) problem, but one more to "file away" in my mental Rolodex---rich