no lockup

drolleman · Newbie Joined: Aug 22, 2006 Posts: 4

I purchased a gmc 82 truck with a 4l80e and a pcs controler. i just had the tranny rebuilt and every thing works but the lockup. a friend with an oscillisope looked at it and found a signal when lock up should happen but no lockup. we then on the road and tempoary shorted the line to lockup and lockup worked then removed the short to the solonoid and then it unlocked. the tranny was a 97 and due to dammage we rep[laced it with a 92 version is there a diffrence? the previous owner was unsure about it ever locking up. i understand if you short the lockup too long that burn out. is there something i could check / set to rectify this problem?

jballenger · Posted: Wed Aug 23, 2006 1:55 pm Post subject:

If you ground the solenoid for too long it can overheat the tcc lockup solenoid. Please send me your calibration file (retrieved directly from the TCU) and if possible a datalog taken while the truck should be locked up at james@ptcs.us. Do you see the tcc lockup light turning on in the software monitor screen?

There is a difference between the 1992 and 1997 4L80E. Did your 1992 have a different connector than the 1997? If so, did you rewire this yourself?

This is the diagram for the 1991-1992 GM 4L80E:
http://www.powertraincontrolsolutions.com/download-file-61.html

This is the diagram for the 1993+ 4L60E/4L65E/4L70E/4L80E/4L85E:
http://www.powertraincontrolsolutions.com/download-file-12.html
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drolleman · Newbie Joined: Aug 22, 2006 Posts: 4

i also set it to default settings and still no lockup.

The truck is 60 miles away so getting the file will be tough.

the lockup light is on when expected.

The tranny shop put the new 93+ connector in the 92 tranny, so no rewireing was required.

when i go out to the truck again what should the scope see when locked up?

is it possible the tcc Solenoid is diffrenent between the two trannys? like the pressure solenoid ?

jballenger · Posted: Wed Aug 23, 2006 5:14 pm Post subject:

When you tested the TCC lockup function, what wire did you short and did you short it to power or ground?

"i also set it to default settings and still no lockup. " Do you mean the base 4L80E calibration file provided with the software installation?

"when i go out to the truck again what should the scope see when locked up?"

The TCC lockup solenoid is controlled from two sides. We provide one side with 12 volts through our wiring harness on Terminal "E" on the 4L80E connector. We provide a PWM (pulse-width modulated) ground signal to the other side of the solenoid through the TCU on Terminal "S" on the 4L80E connector. You should validate the following:

1) When you disconnect the TCU and backprobe terminals "E" and "S" at the 4L80E connector, you get between 11 and 17 ohms.
2) When you connect the TCU, power it up and backproble terminal "E" at the 4L80E connector, you get +12volts.
3) You see a pulsed ground signal on your scope when you backprobe terminal "S" or the violet/red wire on the TCU harness.

I would also recommend that you print the two wiring harness diagrams and show them to your friend with the scope. Specifically the 4L80E key on page 2 of the 1993+ diagram, the 4L80E key on pg 2 of the 1992 diagram and the sub-harness on pg 3 of the 1992 diagram.

"The tranny shop put the new 93+ connector in the 92 tranny, so no rewireing was required." The internal wiring for the 1992 tranny is different. The TCC solenoid is on a separate power bus. On the 1992 tranny, it has power and ground directly routed to it, it shares no wiring with other solenoids. On the 1993+ tranny, the power is shared with the shift solenoids. There is a good chance there is a problem/incompatibility in the wiring here. You will see this when you try to perform the above 3 tests.

When you tell me you are shorting wires and measuring the lines with a scope, please tell me which wires you are measuring (colors or pin positions) so I can help determine the issue.
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James Ballenger
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drolleman · Newbie Joined: Aug 22, 2006 Posts: 4

When you tested the TCC lockup function, what wire did you short and did you short it to power or ground?

to ground

1) When you disconnect the TCU and backprobe terminals "E" and "S" at the 4L80E connector, you get between 11 and 17 ohms.
2) When you connect the TCU, power it up and backproble terminal "E" at the 4L80E connector, you get +12volts.
3) You see a pulsed ground signal on your scope when you backprobe terminal "S" or the violet/red wire on the TCU harness.

1) when i get back i'll check this
2) 12v was present on pin e
3)the signal was a 60hz signal aprox 70 % duty cycle to ground

I would also recommend that you print the two wiring harness diagrams and show them to your friend with the scope. Specifically the 4L80E key on page 2 of the 1993+ diagram, the 4L80E key on pg 2 of the 1992 diagram and the sub-harness on pg 3 of the 1992 diagram.

we had already downloaded the diagrams, and used them for reference.
the trany shop stated that ithe internal wireing conforms to the new 93+ wireing diagrams. they also supplied wireing diagrams.

When you tell me you are shorting wires and measuring the lines with a scope, please tell me which wires you are measuring (colors or pin positions) so I can help determine the issue.

we probed the pin s for tcc-.

jballenger · Posted: Thu Aug 24, 2006 11:49 am Post subject:

Great, nice response the detail is very helpful.

"
1) when i get back i'll check this
2) 12v was present on pin e
3)the signal was a 60hz signal aprox 70 % duty cycle to ground "

1) let me know
2) that is good and is exactly what it should be
3) This is good and exactly what it should be

If the TCC solenoid exists between terminals "E" and "S", then based on answers 2 & 3 above it should have +12v applied to one side and a 70% duty cycle signal applied to the other side. This should activate the solenoid. I am not sure why grounding the "S" terminal is locking the converter because our controller is sending the same signal to the "S" terminal. You can use our software to increase the duty cycle to 100% to perform a test to determine if lockup is occuring between 70% and 100% duty cycle though this should not be an issue as the solenoid begins to saturate at 70% duty cycle.

Can you retrieve your calibration from the TCU and send it to me? Can you perform a datalog when the TCU should be locked up and send it to me?
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James Ballenger
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drolleman · Newbie Joined: Aug 22, 2006 Posts: 4

I had my buddy to check the solinoid and it was 41 ohms. the tranny shop is going to replace it.

jballenger · Posted: Thu Aug 24, 2006 2:37 pm Post subject:

The shift solenoids should be 20-40 ohms though 41 ohms is far too high for the TCC solenoid. Replacing the solenoid is a good idea although I am still leery of a wiring issue.
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James Ballenger
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