Driving my '90W-350 360 TBI/A-518 home yesterday and the trans acted like it was slipping. Came here to the forums and read some related posts and figured out it was jumping out of o'drive. The possible fix that was suggested: change out the signal generator on the speedo drive. Had a spare so I did that. Wow, truck shifted better than it ever has before and it wasn't jumping out of o'drive any more. Problem solved!?

Driving to a friends house tonite and guess what? Yep, tranny went nuts again. WHAT'S GOING ON HERE? Well, I remembered that when I drove it after swapping signal generator that it was warmer outside. Now it was cold out and the tranny slips out of OD. Putting 2 and 2 together I reached up and shut off the heater. PRESTO, no more jumping out of OD!! I played around some more and discovered it only does it when heater blower fan is on 'High'.

I don't ever remember hearing anything more bizarre related to a vehicle problem. Just thought I'd run it by you....

 

Welcome to world of Dodge-Chryco-Mopar electrical gremlins.

 

Is it slipping out of other gears as well, or just out of overdrive? By that I mean have you ever put it in drive or reverse, and stepped on the accelerator and it felt like it was still in neutral? If it is just with the overdriive, if you figure anything out let me know! I have had the same sometimes work sometimes not problem since I had my truck, and tried and looked at everything I could think of.

 

You right, ACE! Exceeding weirdness....

Well, Ira, yes and no. There seems to be another problem in the mornings when it's cold of not wanting to go in gear. Cleans up after about 2-3 minutes and could be the TC or need for fluid/filter change. The problem I'm describing is only an OD problem and apparently it's only when the fan is on high.

Gotta look at the schematic and see how they did the grounds. OD switch is about 2-3" away from Fan speed switch so might just be a simple feedback loop in the grounds or something. OD is connected to computer controls but I'm pretty sure Fan switch is not, so I don't suspect a computer problem.

I wouldn't normally post a gasser problem here in the 1st Gen Diesel Forum but it seems to me it applies to diesels as well and might help somebody. That or we can go nuts togethe on the buddy plan.....

 

Has your transmission ever been rebuilt? There is a common problem regarding the not wanting to shift when cold with transmissions that have been rebuilt. It is my understanding that the 727 and A518 automatic transmissions need a special anaerobic (oxygen fearing or without the presence of oxygen) sealer used around the pump inside the case... Most rebuilders do not know or care about this, so they just use a normal sealer. This, in turn, does not make the correct kind of seal, and you have to wait for it to warm up enough and expands to fill the gaps… I seen this in a Four-Wheeler Magazine article a while back (I will try to find it). My brother had a 727 doing the same thing in a Wagoneer, and he said he adjusted the bands and it worked just fine.

When I first had overdrive problems, I looked everywhere for it and it turned out to be my crank sensor. I replaced that, and it worked well for a while. I read your article this morning, and on my way to work and I tried the blower on high thing. My truck would not shift into overdrive till well over 45 with the blower on high, and really did not want to stay there. I put the blower speed to the next speed slower, and it shifted in at a little over 40. It still popped out once in a while, but was not nearly as bad… I have NEVER seen any make of vehicle with a worse wiring system than Chrysler. I always wanted to know who the drunk chipmunk that they hired to deal with the wiring was… Then I realized a drunk chipmunk could have done a better job…

Going crazy? I think we already have gone crazy. I mean, seriously. All the 1994 and later Dodges out there and we stick with the pre 1993s… Aerodynamics of Rosie O Donald, bouncy stock seats that cause you to hit your head on the ceiling, so many interior squeaks that you would think you had a mouse farm in the cab… My ex-fiancé told me that I needed to get a new truck or she was leaving. I must admit, I sometimes miss her… They have their problems, but I love my truck. Let me know if you find out anything more about the overdrive, and thank you for your information so far, I really appreciate it.

 

These trucks are wired worse than a cheap kit car. Why don't you just wire up a switch on the dash to control the overdrive and be done with it? I did it to mine and it was one of the best mods I ever did. It's in when I want and not when I don't.

 

"My ex-fiancé told me that I needed to get a new truck or she was leaving. I must admit, I sometimes miss her…" Ha haaa !

Chrysler Corporation has been at the top of the heap for engineering excellence for well over 50 years. For just about as long their electrical systems have been dismal in many respects. Overall I really like my '90 Power Ram except for one major exception: GASSER! That would be okay but the miserable computer stuff and all the goofy sensors etc. just stinks! If I decide to keep it there's a Cummins in its future. Before the tranny silliness it was for sale.

I don't know if the tranny was ever rebuilt. The slippage isn't a big deal as long as it only does it in the mornings for a couple of minutes, but it's for sale regardless.

Thanks for the good tip, Johnny! I've been so busy working on the other truck converting to Cummins that I was too burned out to even think of that. Simple, cheap and it works. I like that. Good idea!