Engine/Transmission (1998.5 - 2002) 98.5 shifts in and out of OD

[DKothe]

I've got a buddy who's 98. 5 3/4T auto is giving him some weird shifts.

It shifts in & out of OD between 40 and 50mph (especially with a load). With OD disengaged shifts in and out of 3rd between 25 and 35mph.



Anybody have this happen to them? Is it the transmission or something to do with the APPS?



Thanks

 

[01smokinram]

If i'm not mistaken there is a way that can be fixed. You'll have to take it to the dealer and have the reflash done on it. Wait till you get a few more posts on here before he takes it to the dealer. That's what i heard that'll fix it. I don't have first hand experience because i've never had mine in for the reflash.

 

[Tom W]

It's probably the electrical noise problem. Do a search, many posts on this. Get a noise filter from DTT. 1 866 504 4002

 

[rblomquist]

It's the TC locking and unlocking. Do a search for recalibrating the APPS and try that first; doesn't cost anything and a lot of us have to do it every once and a while.

 

[Mike49]

My 98. 5 did the same thing. I disconnected the batteries and let it sit overnight, then retrain the APPS. I finally put DTT's filter on and no more problems. It happened about once a month without the filter installed It was worth the few bucks it cost.

 

[DPulis]

Look at this....

try the brake pedal switch... some times it gets to close to the pedal and then every time u hit a small bump or get a small jiggle it makes the brake hit the switch and unlocks the torque converter and makes it go in and out of over drive..... or reset the ECU



1. set parking brake

2. unhook both negative terminals on batterys

3. turn key to "on" position leave over night or at a minimum of 30 minutes

4. next morning turn key off

5. hook batteries up

6. turn key "on"

7. press gas pedal "slowly" all the way down and let up slowly...

8. turn key off

9. release parking brake...



APPS is reset.....

 

[wtfd6]

i would also check the throttle positions sensor for a glitch. between the brake switch and the tps i have seen alot of headaches taken care of easily.

 

[c.e. linker]

there is a grey ground cable between battery and airbox on passenger side. take the grey connector apart and clean it out good. put together and pull apart several times to clean the connection. 9 times out of 10 this is the problem with bad ground connection.

 

[AHughes]

I have a 98. 5 also and had the transmission seeking. Called DTT and talked to Stephen and he sent me a filter box under $40 and that solved the locking and unlocking problem. Had the filter in two or three days they ship out of Washington State. I would recommend DTT for all transmission related needs. Oo.

 

[DKothe]

Dtt??

Where and who is DTT? I looked thru the TDR links but couldn't find anything with a DTT address on it.

I'm sure my buddy really appreciates all the help guys!

 

[fox]

DTT



Or 1-866-504-4002

 

[Charliegeis]

I have a '99 that started doing the lock/unlock of the torque converter. Cleaned the battery terminals and added the DTT filter unit to the throttle position line and cleared up the problems. I am sure the DTT filter is nothing more than a capacitor that has been nicely packaged.

 

[24vtrbo]

I had the same problem with my 98. 5. Joel at J&H Performance looked at my batteries and noticed they were forming acid on the terminals, he told me that when the batteries become weak it effects the PCM. I replaced the batteries and it cured the problem.

 

[cosborne]

I too was having the unlock/lock problem. Had it to the dealer a couple times for the reflash... . my PCM would not accept the reflash. Dealer told me to clean my grounds... . which I thought was goofy because my truck is IMO pretty clean. I took the wire off the APPS out of the bundle and tapped it directly to the PCM signal in wire and reset the APPS. This worked for about 2 days, then it started in again. I almost bought a new PCM but thought about the cleaning the grounds comment. I removed the battery cables and the surrounding grounds, the grounding strap the goes from the frame to the block underneath and any other "ground" wire I could find. I took a wire brush to all the connections and re-connected everything. ALL IS FIXED. It's been 2+ weeks now and it seems to be all cured... . I'm still crossing my fingers... .

 

[DDeputy]

OK after reading all these posts I have a question... I have 318+K on my 98. 5 auto. It shifts hard when I 'get on it ' even a little and seems to hesitate slightly before shifting also hunts between OD and 3rd (45mph) and generaly seems to slip upon acceleration. Had a new TP at about 200K and have been considering a new trany. I more or less ruled out the suggested fixes, TP,grnds,and filter. comments?

 

[Rammin]

I had tne same problem sifthing in and out of over drive on a 99. there is a TSB no. 18-02-99 for a reflash of the PCM the PCM is picking up a noise from the altanator the reflash stops this. fixed mine.