A4LD "Please help need advice"

[derangedone]

Hi I am starting a new thread here as the new one was getting to be a cluster and I know a little more about what is going on now. I thought I was having a torque converter lockup issue and may still be but after lots of testing and reading I know now that I have no 4th overdrive gear and the torque converter may only be soft locking. I do have a Rear antilock brake light on, however I have tested the purple wire w/ yellow stripe off the pcm and the orange one for 3-4 shift. Both appear to be getting 12.4V until the PCM kicks them on then I get 0.42V Is this correct and the way it should be? I have unhooked one solenoid at a time by cutting the wire on the fender well, I did not notice a difference with the 3-4 solenoid disconnected. I did notice a difference when the tcc lockup solenoid was disconnected though, the rpm's were around 200 higher, however when I let my foot off the gas at 60mph the engine falls to a idle instead of keeping up with vehicle speed?????? Things I have done to fix this issue is= I rebuilt the valve body " it was extremely clean and every valve was removed effortlessly", installed shift kit and new boost valve, new TCC and 3-4 solenoids, I have tested the wiring on fender to the solenoids and got .26 ohms. " cause I failed to test wire harness under trans pan" The truck runs about 2700 RPM or so at 55mph I feel the torque converter lock in and thought it was possibly the 3-4 shift but it isn't, hardly anything happens when shifting to drive from OD I feel a little jolt I figure it is the TC. I have tested engine with my Actron111 scan tool several times with no engine codes, it knows the vehicle speed and the rpm. I have changed the VSS in the rear diff in a attempt to get rid of the rear anti lock light but if this was causing a issue the pcm wouldn't send a signal from 12.4V to 0.42V would it? The only thing I can think to do now is pull the OD servo and see if it has a issue? Could the Servo for OD if it is bad also cause the torque converter no not lock all the way or will a torque converter only lock all the way in OD? It has me confused cause it seems like 2 different issues and that is usually a electrical issue but I know for sure the 3-4 isn't working. If I remove the Servo I am probably going to be cutting some exhaust pieces cause they are not going to unbolt I can tell ya that much This is also a Jasper transmission and I have no idea when it was installed. everything that I saw inside looked clean and no broken pieces in the pan " a little grey gunk on the magnet but fluid isn't burnt. What would you guys do? looks like the cats are about 2" away from the OD servo!

 

[derangedone]

I went ahead and removed the OD servo, it looked like new. I figured it wouldn't be that easy!

 

[JK080]

See how many turns the overdrive band adjustment turns in until it tightens, if its more than 3 turns the overdrive band could be broken.

If the band tightens then leave it tight, set the vehicle on the ground, start the engine and put it in manual low. The transmission should be in a bind and not move, don't force it to go, just see if it will move with a little gas. If it moves forward the input sprag race on the overdrive planet is broken.

You can also run the vehicle up to speed for overdrive (on a lift or if you are brave on jack stands) and tighten the overdrive band adjustment in till tight, this should give you a 3-4 shift and you will know its a control problem and the trans is capable of 4th.

Also if the 3-4 shift valve moved the servo cover should be very tight to push in, this will tell you the valve body did its job and its a internal failure.

 

[derangedone]

Now that's the kind of advice I am looking for! Thanks JK080, I will do just that. I hope I do not have too much problem with the band adjuster though as it looks a little rusty but I think I can get by with some PB Blaster and by backing off the nut just a bit first, I am sure the adjuster will move with the nut at first but I think I may be able to get it loose, being carful not to back it out to far I hope! This is a Jasper rebuild of some kind and the truck is a 92 so I have no idea if it is the double band or single? I am going to assume it is a single and adjust it as one if this test procedure proves the band isn't broken. I don't think it is broke but not sure, most folks say you will find remains in the pan and this truck has been drivin years like this so I would assume the broken parts would have ended up in the pan but who knows, I bet the sprag is busted knowing my luck that sound like the most common thing but I am ready to find out man! Thanks a bunch

 

[derangedone]

Hi I got around to checking the truck tonight and I put 10 ft. lbs. "120"lbs on the OD band adjuster and put the truck in 1st gear, the trans was indeed in a bind. I backed the adjuster off 2 turns and took it for a drive in hopes the adjustment might do the trick! I think I turned it in more than 3 turns to get to 120 inch pounds I was hoping it was just out of adjustment but nope. if it was a electrical issue like my RAB light then the wires for the solenoids would stay at my 12.4 volts wouldn't they? the lowest reading I get on both solenoids is .040V? Thanks

 

[JK080]

A test light is a quick way to get some answers. I not sure what RAB light is.


There has to be 12 volts on the center pin in the case connector, the computer will make a ground on the pin towards the front for 4th gear. So if you connect the test light to 12 volts and probe the front wire the light should light when the computer shifts to 4th. You can also check the TCC the same way.

You can also supply the 12 volts to the center pin and ground the front pin manually to see if it shifts to 4th.

 

[derangedone]

Hi RAB= Rear Anti Lock Brakes I may try to test again the way you explain, all I did was take a voltmeter and attached black to ground and measured voltage in the solenoid wires while driving when the computer tried to engage 4th and tcc voltage fell to 0.42 volts. I may also try to hook switch up to engage 4th. thanks