Conveter lock up problems- please help!

[FARMFUEL]

Hi there,

Well I'm writing in hopes that someone can bail me out on this 94 IDIT with a E4OD. The motor and trans only have about 3K miles on them, but just last night, I noticed what seems to be an issue with the converter locking and unlocking- running 60mph down a flat road, at part throttle, without moving my foot. It will go from 1,800 to 2,000 and back. It will do this repeatedly until i have to either let off the throttle, or apply more throttle.

I was thinking it may have something to do with the converter lock up solenoid, but I couldn't find one that is by itself in the valve body. Maybe its part of the solenoid pack?

I installed a new MLPS (correctly, with that overpriced tool), as well as a FIPL, which has the voltage set correctly. I've driven this truck for a while now, and haven't had any problems until just now.

Any help would be greatly appreciated. I've sunk a ton of $ into this transmission, and I'm terrified of frying something.

 

[FARMFUEL]

So I'm scratching my head, wondering how LED taillight bulbs would have something to do with shift performance. I could understand the coast switch being tied into the brake light switch, but is it possible that me having LED bulbs would be making this problem? I will report back once I find out later today, but any input is much appreciated.

 

[snicklas]

I would say it is possible, but I have not heard anything specifically about them. The system does pass a small amount of current through the brake light system that does have control over the transmission. The problem I have heard about this is the LED's will stay lit all the time because this small current is enough to light an LED, but not a normal incandescent bulb.

I do know that if you have a shorted brake/tail light it can cause the converter to unlock, but most see this when the turn signal for only 1 direction is on, as the light flashes, it will cycle the converter lock, like during a pass on the interstate.

If you have the old bulbs still handy, that could be a quick check, to just throw them back in and take it for a drive. I don't have anything with LED's on the vehicle, just a trailer, so not sure what LED's could cause.

 

[laserjock]

Do you have the resistor pack wired in line for the LED lights? I have read several guys report random electrical problems because the systems resistance as snicklas mentioned is low enough to let the lights backfeed and do weird stuff.

 

[FARMFUEL]

well gentlemen, I installed a set of incandescent 3157's back into the truck, and wallah- problem solved. Installing LED's on my motorcycle makes the relay cycle faster, so I know that a resistor is helpful in this application, but wasn't aware of a resistor for the 3157. This just blows my mind, how the lack of current drain can cause such an issue. After the incandescent install, there is no noticeable rpm change at 60mph. I guess i never really thought how disappointed I would be in having auto trans problems before. This is the first auto tranny that I've ever owned that I've sunk money into.

Thanks for the help; I really do appreciate it!

 

[trackspeeder]

LEDs don't provide enough resistance to signal the TCM that they are activated.

 

[FARMFUEL]

Well, so I guess I threw a party too early; the problem is back. It only does it every so often, and only around in the 55-65mph range. I bought a Baumann programmable transmission controller, and was planning on taking vacation time to write software programs, but looks like I'm gonna have to speed things up a little and wire it in this weekend. It looks pretty complicated, and I'm as dumb as a box of rocks, so wish me luck! One cool thing about the ability of writing your own shifting programs is that you control the lockup schedule based on mph, so this converter will be locking up after OD, and will unlock at 3/4 throttle, so there won't be a need to drop down to third.

I probably need to get under there and check the solenoid pack connector, as well as the the MLPS connector, but the MLPS and the connector are both brand new, as well as the FIPL. I have the FIPL voltage set at .85V with KOEO. I know this is a little low, but when it's at 1.20V, it shifts way too damn late, killing fuel economy.

I was researching the torque converter lockup mod in the tech articles, and noticed there was a mention of the converter locking and unlocking repeatedly in OD. This is my symptom to a T. I've looked everywhere, and can't find a solution. Still good to know that I'm not the only one that's had this problem.

 

[FARMFUEL]

I know the BOO switch works, cause i can unlock it while going down the road, I just wish there was a way to intercept the converter clutch solenoid wire to see if the TCM is commanding it to be disengaged. Does the CCS work off of ground? maybe I can isolate the wire in the solenoid pack, pierce the insulation with a jumper lead, and hook up a test light inside the cab? It would be cool to run down the road and see if the light comes on or not. That way I would know if the problem is electrical, or perhaps something in the front pump? Everything is new though, I just don't get it...how much $ do I have to throw at this thing, already!

 

[trackspeeder]

The solenoid pack is switched by ground.

 

[FARMFUEL]

Okay, thanks. Good to know. Now: got any idea what wire it is? I can run a jumper lead down there and bring it in the cab, and hook a test light up to it.

So, is it possible that if the FIPL voltage is too low, it will cause this problem? I've been known to jack with it from time to time in an effort to get it to stop shifting at redline!