Transmission Slip Error Code

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Apr 29, 2010 | 01:09 PM

redman84

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Cargo Master

Joined: Feb 2010

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From: College Station, TX

Transmission Slip Error Code

I am throwing a P1728 (transmission slip error code). One shop told me I needed a rebuild. Another told me they aren't sure of the problem because it could be the tranny slipping or it could be something fooling the truck into thinking it is slipping. When I get the codes cleared it runs smooth as butter until the OD light starts blinking again then it shifts super hard from 1 - 2 and harder than normal through the rest. I've noticed a significant decrease in fuel mileage and it seems like my cruising rpm's have raised some as well and they fluctuate more than normal up and down hills on the highway. I don't feel the tranny slipping but could the increase in rpm's signify engine compensation for a slipping trans?

If I do need a rebuild, any suggestions? I don't mind dropping it to take in and save money but would rather do it myself if possible. Advice there? I'm transmission ignorant but quite mechanically inclined. I've taken on many complex projects with success but none so complex as an auto tran.

Please help guys. Y'all have helped me through so many things with my rig so far and this may be the only big thing holding it back from its peak performance.

Apr 29, 2010 | 01:16 PM

Cuda_jim

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Joined: Oct 2003

Posts: 5,903

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From: MICHIGAN

Pretty sure that's a torque converter slip code. The hard shifts are the trans protecting itself from slipping/overheating....normal. It will go way when the code/problem has been repaired. Changing the fluid and filter might help, but.........A new triple disc converter may be in your future.

Apr 29, 2010 | 01:30 PM

redman84

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Joined: Feb 2010

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From: College Station, TX

Thanks Cuda_jim. Any idea on diagnosing? I don't want to fix a non-problem and ignore the real problem. Is swapping the TC something to be done at home? Lastly, could it be anything to do with the solenoid block?

Apr 29, 2010 | 02:44 PM

strokersace

Fleet Mechanic

Joined: Dec 2007

Posts: 1,766

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From: Hutchinson, KS

Yeah, Jacob it could be the solenoid as well. I've got a bts in my truck right now that just out of nowhere started flashing the od light and throwing this code. I can clear it and it comes right back. Exact same symptoms as you described with the rpms and everything.

Spoke to Brian and he said that's the downside to the E4OD's is that you get a very generic code and it can be several things causing it. I haven't tested it yet, but will be testing if it's the solenoid within the next week or so. Gonna do this before I order up a new t/c. Hopefully it's something simple but I don't know.

Apr 29, 2010 | 04:38 PM

Cuda_jim

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Joined: Oct 2003

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From: MICHIGAN

Quote:

Originally Posted by redman84

A good quality scanner and operator should be able to see if the solenoids are switching. Some trans shops will scan it for free, it's worth a shot. It needs to be driven with with the scanner for a good diagnosis.
Swapping the TC depends on your capabilities....mostly bull-work, the trans needs to come out or at least shoved back far enough to get at it.
We have a few guys here that really know there stuff on these things, wait for them to chime in.

Apr 29, 2010 | 06:16 PM

strokersace

Fleet Mechanic

Joined: Dec 2007

Posts: 1,766

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From: Hutchinson, KS

Quote:

Originally Posted by Cuda_jim

The problem is the scanners can't see the E4OD like they can with the 4R100. The only thing a scanner will tell you for our trannies is that code he's already getting. Nothing else. That come from Brian at BTS. He said the newer autos are way easier to find a problem and diagnose it than the older ones are. If we've got tranny problems, that code he's getting is the only one we'll see.

Apr 29, 2010 | 07:19 PM

redman84

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Cargo Master

Joined: Feb 2010

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From: College Station, TX

Quote:

Originally Posted by strokersace

I haven't tested it yet, but will be testing if it's the solenoid within the next week or so. Gonna do this before I order up a new t/c. Hopefully it's something simple but I don't know.

Thanks man. Let me know what you find out. It will be at least that long before, monetarily, I can do anything with it anyway so I'll just be limping it around. Hopefully both of ours will be the solenoid! Fluid/filter change, unplug old, plug in new, wham bam thank you maam, strokersace and redman back in business. At least that's how I picture it...