Transmission connector broke on 4L80E

[Matthew Jeschke]

I have a friend with a 1993 3/4 ton Suburban. It has the 454 and 4L80E transmission (or heavy duty). I don't know much about these years or those builds to be honest. I maybe way off. They sent me pictures, it looks like the transmission connector broke off on the engine / chassis side of the harness, not on the transmission side.

Anybody know much about these harnesses? Where and if a new one can be bought?

Thanks!

 

[OR VietVet]

@rockola1971

 

[89Suburban]

@PrecisionTransmission

 

[rockola1971]

The chassis side plug looks fine from what I can tell in the pics. I cant see the female pins to verify. The tranny side wiring receptacle has 2 guides/locators broken off. I circled the ones broken off in yellow in pic attached of a used one. The locators are there to key the receptacle so the plug can only be fully installed the correct way because the plug has matching female holes which receive the locators from the tranny receptacle. This prevents a numbskull from installing it incorrectly and pushing pins out the back side of the plug or the receptacle or just demolishing them. A new receptacle is not needed as long as the installer pays attention to orientation of the plug while installing it on the receptacle but if a new one is wanted then any tranny shop should have one in stock or can get fairly fast. Keep in mind this pinout was only used in 1991-1993 model years. The 94-03 receptacle with wiring harness is compatible in the tranny case and valve body BUT the chassis side plug of the wiring harness will have to be updated to the 94-03 plug style also. That all can get expensive and time consuming for someone that is not well versed in proper wiring harness rapair techniques but definitely not impossible for the DIY.

 

[Matthew Jeschke]

Ah good, I couldn't quite tell what was wrong in pictures. Also never saw a harness like that. Actually looks better than new design with that screw.

Do you of a transmission parts distrout or that still sells these?

 

[rockola1971]

Ah good, I couldn't quite tell what was wrong in pictures. Also never saw a harness like that. Actually looks better than new design with that screw.

Do you of a transmission parts distrout or that still sells these?

You are more likely to find NOS part from a local tranny shop or on a GM dealers parts shelf with a 1/2" of dust sitting on the package. This tranny (receptacle) and chassis (plug) harness has been superseded and its revision has even been replaced/superseded multiple times now.

 

[Matthew Jeschke]

Yeah, kind of what I feared. It's likely not made anymore, only found in old forgotten parts bins.

 

[Hoesgottaeat2]

No chance of a parts yard nearby to pull one from?

 

[Matthew Jeschke]

Maybe... I go to junkyard here quite a bit and never see trucks that old. Most of those of that vintage here have been crushed.

I think rebuilding the actual connector itself is the route to go. Otherwise, replacing entire harness, but that would require opening the transmission. I've done a 4L60E but I see that connector is coming out side of case... On a 4L60E the internal harness can be easily changed by dropping the pan.

Anybody know if it's the same way on a 4L80E?

 

[Eman85]

Same difference changing on a 4L80E, mine was leaking fluid through the harness. Mine is newer but I found a factory harness available on Amazon.

 

[Matthew Jeschke]

@Eman85 could you get to the entire harness when you dropped the pan? Or does it require more?

I've only done a 4L60E. Not sure if it's similar?

 

[rockola1971]

Maybe... I go to junkyard here quite a bit and never see trucks that old. Most of those of that vintage here have been crushed.

I think rebuilding the actual connector itself is the route to go. Otherwise, replacing entire harness, but that would require opening the transmission. I've done a 4L60E but I see that connector is coming out side of case... On a 4L60E the internal harness can be easily changed by dropping the pan.

Anybody know if it's the same way on a 4L80E?

Yes both the 4l60e and 4l80 and their variations, the tranny side receptacle has to be pulled from inside the tranny case which of course means the pan has to be dropped and the wiring that comes from the receptacle has to be disconnected from the shift solenoids, tcc lockup solenoid, etc.

 

[Matthew Jeschke]

Oh that's not too tricky. Maybe easier to just swap out the whole harness. I know there's different pinouts between different years. I used to have a chart with all that stuff but cannot recall where I saved it.

 

[Rocket Man]

You can get both the internal transmission harness complete or for the vehicle side you can buy the connector with pigtails on it and you have to cut and splice the wires. They have butt connectors now that heat shrink around the wires for a water tight connection. I solder and heat shrink my wiring but the butt connectors are easier.

1993 CHEVROLET K2500 SUBURBAN 5.7L V8 Automatic Transmission Connector | RockAuto

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www.rockauto.com

 

[Eman85]

Yes. I dropped the pan and just replaced the whole harness.

 

[Matthew Jeschke]

Thanks! I like the idea of butt connectors that seal up. Seems whenever I solder a connection and use shrink tubing it seals up but the solder joint eventually fails no matter how I solder it. I'll advise accordingly. Doesn't seem to tricky if is similar to 4L60E.

Anybody worked on these older ones with the Transmission control module? It's been so long since I've done that. Are they in the same box as the Engine Control Module or can I pull out that whole harness with the computer to splice in the connector?