93 4l60E (probably electrical) Problem with shifting.

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tayto

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good meter work either way, i hope a new harness fixes your problem. the trans sounds mechanically ok
 

ima93chevyguy

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I had the same issue trans would be stuck in first and I couldn't get it out then it would randomly shift out. Did that for about a month. Then it started getting really weird and shifting erratically. Ordered a new internal harness with all the solenoids and that completely fixed it.

4L60E Transmission Master Solenoid Kit Compatible with 1993-2006 GM EPC Shift TCC 3-2 PWM https://a.co/d/6pU4Un1
**THIS IS NOT WHAT I ORDERED**
This is just something similar to what I ordered I can't remember the website I got it from.
 

Schurkey

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I don't understand how you can have electrical issues that prevent contact to one of the solenoids, and still have functional first gear.

First gear needs both shift solenoids working, which can't happen if the wiring is FUBAR.

Stuck in SECOND gear, I could understand--if the so-called "1--2" shift solenoid is the one that doesn't have wiring continuity, and the 2--3 solenoid functions properly. But then you should also have third gear. If both solenoids have failed wiring, you'd be locked in third gear--but how do you mistake third gear for first? The truck would be a dog off the line.
 

ODaily

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Either the jittery connection allowed it, or I have somehow offended the transmission gods and this was my punishment. Go figure.

I'll get a new harness and we'll know for sure.
 

ima93chevyguy

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Mine would be locked to first completely. Manual shift would not fix. At first it would shift out after driving several hundred feet or maybe even having to stop and shift through the gears. Eventually got to the point I would have to turn it off and recrank it to solve the issue. Then just started shifting and downshifting for absolutely no reason randomly so I parked it.
 

tayto

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when testing continuity did you disconnect both ends of the wire and then ring it out? if you didnt then its not really a valid test. The fact the wire is brittle already tells me it should be replaced anyway. is it possible they told you it was new but its just the original? i also agree with schurkey, if intermittent continuity to B solenoid, you would have 2nd and 3rd (electrically). if there was a transgo HD2 kit installed then you could have manual 1st with the main connector unplugged.....
 

ODaily

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Continuity,
1st check from ECM (still plugged in) to Solenoid (unplugged). (tranny plug still connected)
2nd check from ECM (still plugged in) to Wiring harness Trans Plug (unplugged).
3rd check from Transmission connector (definitely unplugged) to Solenoid (unplugged).
All 3 good on the green wire, 1 and 3 bad on the yellow wire, 2 was good on yellow.


is it possible they told you it was new but its just the original?
This is confusing. I'm not sure if you mean the person who built the trans? Just to clarify, I built the trans with my own two hands. I bled, sweat, and cursed it into life. The only help I had at all was when a buddy helped me unload the core out of the trunk of the car I had to use to go get it.

If maybe, you mean the company that sold it, it was pretty obviously new manufacture when I unbagged it. In retrospect, I think I bought a unit constructed with the cheapest possible wire they could get, that clearly can't stand up to a 2 year soak in ATF.



i also agree with schurkey, if intermittent continuity to B solenoid, you would have 2nd and 3rd (electrically). if there was a transgo HD2 kit installed then you could have manual 1st with the main connector unplugged.....
I have no explanation. But I do have a little more information. The trans was built with Sonnax parts right to the spec of their level 2 build, with one exception. I orginally installed the billet 2nd gear servo used in their level 3 build, but it was too harsh, and it's been swapped out for a 'vette servo.

So yes on the shift kit, but it's Sonnax.

The only other oddities are,
A. I used a core from a 94. There are minor differences, but very minor, and none that matter from outside the trans.
B. The core I used was a 4WD. I just bought a new output shaft and re-used my output housing. I did this cause I really like the aluminum dust cover, and really hate the stamped steel one on the 2wd models.


EDIT*

Just had a thought about the weird shift pattern. If the cracked insulation allowed the wires to connect somehow. You could only have 1st or 3rd. Solenoid A would power both A and B, and if A was off, then they're both off? Weird as all get out, and totally improbable, but it's the best I've got.
 
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tayto

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you had said it was rebuilt, but not that you DIY'd it, just that you had R&R'd it a bunch of times yourself. doesn't really matter congrats on DIY'ing it. Sonnax has some good parts but a lot aren't necessary. corvette servo is just fine into the 600hp range. i REALLY hope you didn't install their servo release check valve. it should be thrown in the trash...

Sonnax does not make a 1-2 shift valve that will also hold 1st gear to any RPM like Transgo does in their HD2 kit. This valve will allow manual 1st gear with the main connector disconnected and the shift lever pulled into 1st.

It is very possible for 1 solenoid to back feed another if the right bare wires are touching. even if a new harness doesn't fix your problem it should be done anyway. What brand was the harness you bought? I only have experience using AC Delco or Rostra harnesses.
 
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ODaily

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Anybody who sees this DO NOT BUY.
https:// www .amazon.com/gp/product/B01GMZLBV8/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

This has the parts list for all the levels.
I did Level 2. Pretty sure the servo release valve isn't involved.

Harness should be here next week. I ordered a whole front end rebuild even though the pricetag nearly gave me an aneurism.
 

ODaily

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Parts finally came in. Trans is back together, but no fluid and I haven't tested it out yet. Mostly this is because I've dissasembled the front suspension. Thought I could get it done over the weekend, but got shipping borked instead.

I did test the continuity between the A and B solenoid plugs with both unplugged and the trans harness unplugged before I removed the harness. No continuity, so that shoots that theory down. Anywho.

The pictures are there to show the cracked wiring. It needed replaced anyway due to the defective pin in the wiring, but wow. That harness is not very old. I compared the old harness to the new rostra and there are small significant differences. Nothing that affects function, just lets me know they come from different parts in different manufacturing plants.
 

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