93 4l60E (probably electrical) Problem with shifting.

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ODaily

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First the important stuff.
1993 C1500. 2WD. 4L60E.
Trans was rebuilt about 1-2 years ago. Has run beautifully so far.


I developed a leak, and went on an incredible snipe hunt trying to eliminate it. Long story short, I've had the trans out of the truck about 6 times now. Finally found a nearly impossible to see leak in a torque converter weld. Got a new converter, leak stopped.

The time before last (5th time), when I had put it back in, I noticed it wasn't shifting out of 1st. I attributed it to (probably) low fluid, and ignored it as the leak had my attention. Put it back in the shop and pulled it again. (for the 6th time) when I found and fixed the converter leak, and reinstalled.

It still won't shift out of 1st (details to follow). It had never done this before. I think I may have damged an electrical connection during my repeated pull / installs.

Truck takes off fine in 1st. Won't shift unless you wind it way up, and then let completely off the throttle. If you accelerate up further it will be fine for a bit, then starts cutting in and out. Like it's jumping between gears. DOES NOT FEEL GOOD. Don't want to replicate. If you take off in low, you can't manually shift to second. I didn't try shifting it into OD to see if I could coax a shift out of it.

I've double checked the trans fuse.
I visually searched the harness and can find no broken or exposed wires.
I checked the VSS plug and wires as well. Also, speedometer works fine.
I pulled the round main plug, and looked it over, but saw nothing out of place. Hard to see though.

I did take the pan off around the 3rd or 4th time I pulled the trans to replace the front pump gasket. It shifted fine after that, the problem seems to have developed later on.

I still need to get an inspection mirror so I can see into the main plug socket. Maybe I broke / bent a pin.

Question 1. What circuit or part could cause these symptoms if it dropped out of normal operation.
Question 2. Is there a procedure / check list to pull the pan off and check the wiring with a multimeter? As in, this wire should be ground, that one should be 12v, these should be *** ohms?
 

1997

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wow, way to stick with it. you're an expert on getting that trans out.
have you checked for codes? OBD1 can set codes without check engine coming on.

look for code or symptons in here:
https://shop.ukrtrans.biz/wp-content/uploads/catalogs/4L60E_80E_CODE_BOOK.pdf
follow their troubleshooting flow chart, should point you in the right direction.
they have a section on testing with a multi meter.
good luck.
 

Schurkey

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This chart is supposed to be for a 4L60E. I'd be happier if it actually said that somewhere on the chart.

You must be registered for see images attach

If you actually have FIRST gear, both shift solenoids are working. "Limp-Home" mode would be locked in 3rd gear.

I suppose the 1-2 solenoid could be leaking, so that even if it's turned off, it's still flowing fluid...but that seems like a long-shot.

Verify fluid level, maybe toss a fresh filter in the thing. I'd connect a scan tool and see what the computer is trying to tell you. And I would want to know how it operates in "D" and "OD".

If it won't shift to second, one wonders if the 2--4 band isn't applying. Be interesting to connect a trans pressure gauge to the service port(s).
 

ODaily

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wow, way to stick with it. you're an expert on getting that trans out.


After number 4, I threatened to sell it. After number 5, I threatened to burn it.

Codes. Shoulda thought of that. Will check tommorrow, and run the troubleshooting chart with whatever I find. Gonna be something small and stupid, I'm sure.
 

ODaily

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I looked everywhere, but my code scanner has evaporated into the aether. Would the trans codes show up in the blink codes? I think so, but not 100% sure.

I shorted the diagnostic pins and only got a "12", so all clear apparently.
I also stood upside down and sideways to get my head and an inspection mirror into just the right spot. Couldn't see any broken pins.

look for code or symptons in here:
https://shop.ukrtrans.biz/wp-content/uploads/catalogs/4L60E_80E_CODE_BOOK.pdf
follow their troubleshooting flow chart, should point you in the right direction.
I couldn't get into this. Just "The requested URL was not found on this server."
I did get into "https://shop.ukrtrans.biz/" but I can't get google translate to change it from Ukranian to English.

Probably won't be able to get back to it for a couple of days. Maybe Saturday evening. Thinking of pulling the pan to check the wiring harness out.
 
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1997

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12, yep no codes.
ya, that PDF is gone from that site now.
google it, it was posted on multiple sites, if you can't find it, PM me.

Tayto has chimed in, he's the go to guy for trans issues here.
 

tayto

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theres some simple stuff you can do without dropping the oan, jist because the speedo is working doesn't mean the PCM is seeing a signal. the VSS goes to the DRAC and from there the signal gets converted to DC square wave for speedo, cruise & PCM. i would also check things like TPS. again, i do all this with a scantool, you can do it with a DMM also.

please read my post above and try that as well, it is an easy thing to do.
 
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ODaily

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Unplug and try it? Will do. Gotta get it off the jackstands again. My time tommorrow and most of Saturday is borked. But I'll get it done.

Found the PDF, and Holy Hannah! is that complete. Going to take awhile to unpack, and I've definitely got a copy saved off. It's gonna be an interesting read even if it doesn't help.
 
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