4L60E BANG! during kickdown, now no 1st Gear

[AuroraGirl]

Hope it works....

Yes me too, if it does a free transmission fixing a nuked one is amazing
But Im gonna have to force my dad to replace the radiator, cooler. The radiator leaked anyway. Because he would probably just want to do bare minimum and next thing you know granola in the lines nukes this trans. Lol.

 

[AuroraGirl]

Hope it works....

https://www.youtube.com/@ATSGcompany/videos you may interested in following this youtube channel they recently starting posting a lot of transmission issues and their fixes, good visual aids.

 

[NickTransmissions]

https://www.youtube.com/@ATSGcompany/videos you may interested in following this youtube channel they recently starting posting a lot of transmission issues and their fixes, good visual aids.

I am aware of it and subbed. Also get regular bulletins from them, ATRA and several other trade groups and related sources. Also have ATSG manuals for every transmission i work on and even a few I dont (but may in the future). Trust me, Im sufficiently plugged in...

 

[jd33173]

1997 1998 GMC Sonoma (Chevy S-10) 4.3L V6, 4WD, 4L60E

This is the vehicle that had a frozen battery and loose negative cable at the battery terminal. Parked since September-ish because I was told the alternator was defective. I put a battery in it a week ago, tightened the cables. No trans problems noted during that test-drive. Owner drove it ~50 miles today with no notable problems except a MIL illuminated.

Today I tested alternator, works great. Cleared a single code, for evaporative emissions, looked at gas cap, has damaged O-ring.

Decided to be "thorough"; took the truck for a test-drive. ~50 mph, stabbed the gas, trans kicked-down to a lower gear, and as it did--BANG! The whole truck convulsed. Now, not only do I not have first gear when in "Overdrive" or "Drive", but OD seems weak--slippy.

Reverse is good, and truck will move when shift lever is crammed down to "1" or "2", but no (first) gear engagement in "D" or "OD", so the truck doesn't move from a stop in those two positions. It drives reasonably normally if I start in 1 or 2, and shift up manually--although OD is questionable.

Using the scan tool to check--key on, engine not running--I can hear the solenoids click for 1-2, and 2-3 shift solenoids. No codes stored, and no shift adaptions post-test-drive--but I cleared the engine evaporative code before the test drive, so maybe that cleared whatever trans codes and shift adaptions might have been stored.

Fluid level is good, and not burned-looking but is "old" light-red not "cherry red".

Ideas on what I broke? Common problem?

Adding insult to injury, the alternator quit working sometime during this test-drive. I though maybe the "bang" was the serpentine belt breaking, but I wasn't that lucky.

liked "convulsed" not a word you can work into casual convo on the regular

 

[AuroraGirl]

liked "convulsed" not a word you can work into casual convo on the regular

You must not speak to me often (lol jk)

 

[someotherguy]

Pop the pan off and look at what's on the bottom...Same thing I tell everyone else...If you see black clutch material, metal, lots sand-like matter (either silvery or bronze in color), it's more than likely no good. Brown fluid is not an encouraging sign....

Also, make sure your replacement trans is, in fact, a 1996 unit, not a 1995...The 95s have 'PWM' on the front of the pump but the selector shaft is the same length as a 700R4's or 1993-94 4L60E whereas the 1996 selector shafts are longer to accommodate the manual lever position sensor that's bolted to the case over the selector shaft. Also, the 1995s don't have the mounting provisions for the shift cable bracket where as 1996+ do.

Nick you're the expert here and I'm barely an amateur when it comes to transmissions, but are you 100% sure on the 1995 4L60E? One from a GMT400 should have the same selector shaft, range switch, and shift cable setup as a 1996-up. 1994 was the last year for the mechanical rod linkage and string-operated needle gear indicator in the cluster. 1995 got cable operated shift and the individual LED gear indicators in the cluster with input from the range switch.

Richard

 

[NickTransmissions]

Nick you're the expert here and I'm barely an amateur when it comes to transmissions, but are you 100% sure on the 1995 4L60E? One from a GMT400 should have the same selector shaft, range switch, and shift cable setup as a 1996-up. 1994 was the last year for the mechanical rod linkage and string-operated needle gear indicator in the cluster. 1995 got cable operated shift and the individual LED gear indicators in the cluster with input from the range switch.

Richard

They may have started to install them in the 1995 model year, but 1996 was the first full year to the best of my knowledge...A quick check of parts websites has the first gen MLPS showing for 1995-2003 while some show 1996-2003 for the same part (2004-2008 MLPS were different)....The last 1995 unit I worked on did NOT take an MLPS but I don't know what month the vehicle was manufactured in 1995...

While I may be an expert, I'm certainly not perfect so if this is one of those imperfect moments for me, I'll stand corrected...