Engine/Transmission (1998.5 - 2002) DTT filter not working on locking/unlocking problem

[MullinsM]

Background: 99 2500HD 4x4 auto. 200,831 miles. About 5 years ago put DTT filter on to eliminate the transmission hunting around 40mph. This had cured the problem until the last month and now it is hunting around 60 mph. While reading recent questions and doing searches for the problem I have run across two different methods of possibly curing my problem and need some help sorting this out.

1. Was the DTT filter only good for the 40 mph problem and not for the 50+ mph problem?

2. In a post in 2006 the thread talks about a cure from ATS Diesel that involves "tapping" the ground wire from the APPS plus cutting the signal from the ECM to the PCM and rerouting.

3. Also, in the 2006 thread a filter from Happibox.com is mentioned as curing the problem with noise to the PCM.

4. In the recent thread "Locking/Unlocking" the Suncoast method of cutting only the ground wire and regrounding is used.



Questions:

1. Who has experience with the above methods (ATS vs Suncoast) and is one better than the other?

2. Can the DTT filter go bad? If so what would the symptoms be? Was it only good for the 40 mph problem?

3. If you used the Suncoast method did you have a DTT filter? This filter ties in on the same wire that the rerouted signal from the APPS ties into. Did you install the DTT on the rerouted signal?

4. Does anyone have any experience with the Happi box?



Thanks for any help

Mike

 

[Regcabguy]

Background: 99 2500HD 4x4 auto. 200,831 miles. About 5 years ago put DTT filter on to eliminate the transmission hunting around 40mph. This had cured the problem until the last month and now it is hunting around 60 mph. While reading recent questions and doing searches for the problem I have run across two different methods of possibly curing my problem and need some help sorting this out.

1. Was the DTT filter only good for the 40 mph problem and not for the 50+ mph problem?

2. In a post in 2006 the thread talks about a cure from ATS Diesel that involves "tapping" the ground wire from the APPS plus cutting the signal from the ECM to the PCM and rerouting.

3. Also, in the 2006 thread a filter from Happibox.com is mentioned as curing the problem with noise to the PCM.

4. In the recent thread "Locking/Unlocking" the Suncoast method of cutting only the ground wire and regrounding is used.



Questions:

1. Who has experience with the above methods (ATS vs Suncoast) and is one better than the other?

2. Can the DTT filter go bad? If so what would the symptoms be? Was it only good for the 40 mph problem?

3. If you used the Suncoast method did you have a DTT filter? This filter ties in on the same wire that the rerouted signal from the APPS ties into. Did you install the DTT on the rerouted signal?

4. Does anyone have any experience with the Happi box?



Thanks for any help

Mike

Call Stefan at DTT. He's really helpful.

 

[BSander]

The suncoast grounding method with no noise filter has worked very well for me, and I have passed this info on to others. We have two 99 trucks, and the suncoast ground rewire has worked well on both. Not only is this problem cured, but the transmission shifts better, with no hunting or slipping, torque converter lock up is faster and consistant.

I think people are hesitant to do the suncoast rewire because it is so simple and inexpensive, they think it can't work. Well, it does. THe trucks should have been wired this way from the factory. With this rewire and a FASS system replacing the factory lift pump the trucks are much more reliable and run much better; making ownership much more enjoyable and inexpensive.

 

[MullinsM]

Thanks!!!! I also have the Fass fuel pump. I will do the Suncoast and see how it works for me.

 

[Ramtuf1]

The suncoast grounding method with no noise filter has worked very well for me, and I have passed this info on to others. We have two 99 trucks, and the suncoast ground rewire has worked well on both. Not only is this problem cured, but the transmission shifts better, with no hunting or slipping, torque converter lock up is faster and consistant.

I think people are hesitant to do the suncoast rewire because it is so simple and inexpensive, they think it can't work. Well, it does. THe trucks should have been wired this way from the factory. With this rewire and a FASS system replacing the factory lift pump the trucks are much more reliable and run much better; making ownership much more enjoyable and inexpensive.

BSanders



I noticed that in an earlier version of the Suncoast grounding method, they tied the two wires directly to the battery ground. In the one currently posted on their site, they take the two wires into the cab and ground to the dash frame. May I ask how you grounded yours?



I have the Suncoast full treatment in my truck and I'm currently experiencing up shifting and down shifting in my transmission and very frustrated. I tied my wires to the dash frame. I also have done the shielding of the ground wire near the alternator many years ago.



I do have a code that signal voltage of APPS is low which I'm going to clear and also reset the APPS to recommended signal voltage stamped on the pot as I believe this started when I performed the ground reroute. Getting harder to drive truck with transmission up and down shifting (or TC locking and unlocking). Not sure which so trying everything. I don't have any of the filters installed but this just started getting very badl

 

[BSander]

I used the earlier method. I cut the wire, soldered a wire to each end, ran the two wires to the left front of the truck and soldered ring terminals on each end I then removed the ground lug from the right battery (-) calbe where it grounds to the radiator support. I made sure all the contact areas were nice clean metal, then replaced the bolt through the ground straps, grounding everything to the factory ground lug on the radiator support.

The suncoast pdf said to ground directly to the battery, but I felt the method I used was a cleaner, nicer looking connection. My method runs the wire to the - battery cable. Don't forget to disconnect the batteries for a good amount of time, and reset the accelerator position sensor too. I was very doubtful that this solution would work, it seemed too simple and to inexpensive. I am happy to say it has worked far better than my best expectations. Every shift since the modification has been smooth and tight, no more problems.

 

[fox]

I would recommend you call them and ask for advice.

But, disconnect the alternator and go for a drive to see if it still does it.

 

[Bob4x4]

Put a scanner on it and watch what is happening,you could have internal issues or other electrical issues



Bob

 

[Ramtuf1]

Thanks for the replies and comments. Just finished working on the truck this weekend and if it continues to have the problem, I'll take it to a specialist whom Suncoast recommended in my area of the State.



First of all, I shielded the ground wire behind the alternator with foil several years ago (per thread in TDR) and that took care of the first go around with the TC. I followed the Suncoast method currently on their site and grounded it to the dash framework. I removed, cleaned, and reattached many of the grounding points under the hood. I removed, noted the voltage and reset the APPS as close as possible to that voltage reference. I cleared the trouble code and I also ran an individual ground wire to the PCM as well as cleaned their OEM grounding wire connections.



Of all that I have read on this particular problem, I haven't seen anything further. I took it out a few times today and noted no problem at present but it was very intermittent. I checked and I have no codes so far. I can only hope the problem is licked. I originally had 0122 (Low APPS signal voltage). The voltage reference as measured before resetting was considerably low.



I talked with the people from Suncoast and their initial concerns was that the grounding or the APPS was causing the problem. The APPS is original but looked good when using an O_scope to monitor the center tap (Wiper) of the APPS potentiometer. If I still have a problem, I'm going to assume that it isn't the TC but a shifting problem internal to the new transmission.



I'll make further comments when I have new information. Thanks again for all the help.