Erratic Torque Converter
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Senior User
Joined: Mar 2008
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From: Wisconsin
Erratic Torque Converter
Any ideas??? While cruising anywhere from 45-65 mph the torque converter will unlock and lock back up erratically. This doesn't happen all the time. First time this happened was a few weeks ago and didn't happen once we were trailering a car home. Then did it again a few nights ago. Seems like while it's cruising. No OD light flashing.
Logistics Pro
Joined: Jan 2001
Posts: 3,740
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From: Central NYS
Try unplugging the TPS and put an analog ohm meter on it and see if the needle swings smoothly as you exercise the throttle. The TPS may be worn right where it spends most of its time and if it has a few jerky spots right there, it might be confusing the PCM as to wheather it should lock or unlock the TC.
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Yes, the brake lamp circuit is separate from the signalling half of the switch. However, the half of the switch is used for all signalling of the brake pedal position does control the CC and the TCC. It might be the BPP switch... or it may not.
If you have a scanner what can log live data in Mode 6, you can watch the various inputs and outputs of the PCM to see if the unlock/lock is commanded or not. If it's commanded, you can look at the various sensor inputs to see if you can catch the glitch that's causing the symptom.
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Senior User
Joined: Mar 2008
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From: Wisconsin
I talked with a transmission guy and he said to check brake light bulbs and the TPS. He said the same as you pdqford about it wearing in one spot. I will have to get an analog volt meter since digital would work so well. He also told me about a product called Dr. Tranny Shutter fix. Anyone use it before. He said he never recommends additives to transmissions with the exception of this one. He has had excellent results and customers are happy it saved hundreds of dollars. Thanks for the advice so far.
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Postmaster
Joined: Sep 2010
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From: Southern Cal
I talked with a transmission guy and he said to check brake light bulbs and the TPS. He said the same as you pdqford about it wearing in one spot. I will have to get an analog volt meter since digital would work so well. He also told me about a product called Dr. Tranny Shutter fix. Anyone use it before. He said he never recommends additives to transmissions with the exception of this one. He has had excellent results and customers are happy it saved hundreds of dollars. Thanks for the advice so far.
As I've said before in other posts... 300k later and some aggressive towing, a 10k toy trailer and a 25' powerboat, she's still going strong.
I have however, moved to an F-250 6.0L diesel for my towing now with a bigger 15.5k toy trailer.
Hotshot
Joined: Jan 2004
Posts: 19,768
Likes: 1,082
From: St Louis
Checking the brake lights on this truck won't matter, but checking the TPS is certainly a good idea.
I've used the Dr Tranny Shutter Fix before to extend the life of a limping transmission. If your problem is worn clutches or slightly leaking seals, it can help a bit.
I've used the Dr Tranny Shutter Fix before to extend the life of a limping transmission. If your problem is worn clutches or slightly leaking seals, it can help a bit.
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Senior User
Joined: Mar 2008
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From: Wisconsin
This is an intermittent issue. It doesn't do it most of the time and it started just recently. While cruising(55-60MPH) the TC will unlock, rpm jumps a few hundred, then it will lock in again. It will do this for a few miles, I came to a stop then it didn't do it. Most of my trips with it are short with stops. I haven't had it on the highway for an extended period of time to know whether it would correct itself or keep doing it. I am thinking that the TPS could be a possibility. The brake switch maybe since the roads weren't smooth. I don't have an analog volt meter to test so will have to l borrow one. I doubt a coil pack is the issue as there is no change in power, hesitation or stumbling, etc noticed. A brake switch is cheap and easy to replace so I may do it just to rule it out.
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Senior User
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From: Wisconsin
Took it for a little drive tonight to try and duplicate it and I was able to. I have this neat little tool called Scan Gauge II in my Expy. Well, I set one of the readings to TPS so I could see if there was a number that would trigger it. Well, there was. So this is leading me to believe it maybe the TPS sensor after all. Under normal driving at about 57-60mph the gauge was reading 26-28. When I would crest a hill or terrain the number would start to drop and when it would get to the number 21 it would unlock the TC. So I was able to mess with the throttle while cruising and it would only unlock when the number would read 21. Then lock up as the number would increase back up to 26-28. Complete off throttle number was 19. So, TPS??? What do you all think.