E38/T42 4l60E P0717 Code

Hey Guys,

This past year my buddy built an expensive project vehicle with an 08 vintage LS3 and a T42. Someone supplied the harness and modules.

The vehicle didn't start or run, no less shift.

If got it running now with some 2008 Silverado calibrations, but it won't shift and the speedo only bounces.

I believe the problem is that he installed a 4L60e that does not have an ISS sensor and the tcm is expecting it.

I have no definitive answers from anyone that has successfully used a NON-ISS trans with a T42. Turning off

codes or telling the TCM the ISS is not present has not helped thus far.

Anyone have experience with this or can shed some light?

Your thoughts are much appreciated.

Chuck CoW

Hey Chuck, there are a handful of TrailBlazer SS guys running around with non-ISS transmissions swapped in, just by killing the codes and changing the tune values. If that's not working for you, not sure what would solve it as I haven't dug into it before. There must be a way, at least with E67+T42 combo (LS3 to me usually means E38).

We've done all that and still no luck.

The other problem is that we have a very erratic speedo that does not seem to want to behave.

It's an 08 E38 T42 combo originally TIS flashed from a single truck vin.

Chuck CoW

Did you look through the TCM and kill everything released to ISS? P0716 codes as well?

Does it run and drive now, just troubleshooting the P0717 and ISS related codes?

Quote:

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Originally Posted by ScarabEpic22

Did you look through the TCM and kill everything released to ISS? P0716 codes as well?

Does it run and drive now, just troubleshooting the P0717 and ISS related codes?

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Yeah, tried all that and it didn't seem to make a difference.

Strange enough, I got back involved in this thread because a 2007 Suburban came in with a P0716 & P0717

Did lots of testing with it and can't seem to put my finger on it but this kid has had 4 transmissions in the truck

previously and 2 or 3 of them had the P0717 code.... Chased wiring, grounds, replace controller, and all sorts of other

stuff and still every so often it throws the code and while it shifts and drives, the TCM commands max line and it

blasts into second much harder than is acceptable. I've never seen an ISS fail and I've rebuilt many of those units

so this is killing me.... It's a low voltage code, but the solenoids in the trans all share the same power feed....

Up next, Gotta get the pan off and see what there is to see inside.

No fun.

Chuck CoW

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Quote:

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Originally Posted by ScarabEpic22

Did you look through the TCM and kill everything released to ISS? P0716 codes as well?

Does it run and drive now, just troubleshooting the P0717 and ISS related codes?

---

So, now I have another friend who came in with a 09 Trailblazer I5 with an E67 and T42. Same shit with P0716 and P0717 going into max pressure mode.

Disabling the same codes on this vehicle also created a P0741 TCC stuck off condition. The other vehicle did not do this.

This is an E67 / T42 combo.

To the best of my knowledge there is no T42 calibration that does not utilize the ISS for 4L60/70e. If anyone knows of a calibration or application that

does not use the ISS I would love to know about it.

Additionally, the 2 vehicles where I have the ISS turned off and the codes disabled, each person says that the trans is a bit better but the overall trans behavior

is not what it was before the ISS fault happened and was disabled.....

Still a mystery.... Hopefully someone has some input here.

I cant believe that you can turn off something the tcm is expecting to see without consequence.

Iss is used for lots of stuff, especially converter slip and I can't imagine that it can be just "turned off"

Your thoughts?

Chuck CoW

Thinking Out Loud:

besides DTC's, are there any other diagnostic data that we can look at...

for example, will Mode $6 data reveal anything, is there Mode $6 or equivalent for T42...?

09+ may be a different story as that's when GM switched to the internal MLPS, removed a solenoid, and changed the wiring harness (think that's correct).

Weird to hear about the ISS fighting you like this Chuck, not sure why it is. I think you're correct, all T42s had a trans equipped with the ISS...

Hey Joe I don't think efilive ever mapped out mode $ parameters in the trans controllers.... I've never really looked, but don't remember seeing it either.

Chuck CoW

Quote:

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Originally Posted by Chuck CoW

Hey Guys,

This past year my buddy built an expensive project vehicle with an 08 vintage LS3 and a T42. Someone supplied the harness and modules.

The vehicle didn't start or run, no less shift.

If got it running now with some 2008 Silverado calibrations, but it won't shift and the speedo only bounces.

I believe the problem is that he installed a 4L60e that does not have an ISS sensor and the tcm is expecting it.

I have no definitive answers from anyone that has successfully used a NON-ISS trans with a T42. Turning off

codes or telling the TCM the ISS is not present has not helped thus far.

Anyone have experience with this or can shed some light?

Your thoughts are much appreciated.

Chuck CoW

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From reading the rest of the post it sounds like there may be other issues. I have successfully tuned many swaps now with E38/T42 with a 4l60 with no ISS and made them work correctly. They all took some tweaking and not just turning off codes.