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4L60E Full rebuild, now stuck in Limp Mode, I think.
First off thanks for letting me join your forum. I own a 2000 Chevy Silverado 4x4 with the 5.3L 4L60E Trans in it. I bought the truck because the trans was toast, they had no reverse or any other gears. I used the Transmission Bench videos and delux package to replace just about every part in the trans. The valve Body received a new wiring harness,Accumulator Pistons, filter, both Shift Solenoids (Rostra Precision Controls), Manifold Pressure switch (AC Delco),Booster Sleeve and Valve even did the replacement Sonnax TCC regulator valve assembly. Here's kind of a high level summary of what was replaced as well:
Overhaul Package (Toledo)
Filter (SPX/ Filtran)
HI ENERGY Band (Borg Warner)
Friction and steel plates (Raybestos)
Clutch Pistons
Booster Sleeve and Valve
Cooling Line Fittings
Bushing Kit
Accumulator Pistons
Shift Solenoids (Rostra Precision Controls)
Manifold Pressure switch (AC Delco).
Also I've bypassed the radiator, got rid of the old Trans cooler and installed a new Trans cooler, cleaning out the lines from the trans to the new cooler rigorously.
So here's the problem, after I took it for it's first test drive it would not shift out of 1st or even shift at all to another gear, the rpms seemed to stay around 2k. So I'm guessing I'm in limp mode or at least what I"m thinking is first gear but now I'm reading it appears I may be in Limp mode. Currently there MIL light is not on or any codes cannot be found. Now I keep reading most readers are not going to pick up Trans codes so here's what I've tried so far to diagnosis what might be happening:
Verified the ING 0 10A "trans fuse" fuse and it appears good, by appears I took it off and it looks okay.
Verified all the fuses on the box under hood were okay as well
Pulled the 4L60E wiring harness from the transmission and verified that all the connectors on the transmission were okay "no bent connections" etc.
Took a measurement with the Key On, of the Pink Wire, Pin E on the connection and it never measured 12 Volts but maybe between 4 to 7 volts. I was expecting when I took this measurement, with the key in the Key on position to get pretty close to 12 Volts but no measurement has.
So here's my questions:
Is there some type of test while driving the truck I can do , like manually shifting to 3rd gear to see if it will shift down or up and any other gear to see if will shift at all?
Can I check something on one of the fuses under the hood see if I"m at least putting out 12 Volts to the Pink , Pin E wire?
If I'm not getting 12 Volts, to the Pin E, where should I start looking back to trace the source?
Is there some sort of way to actually read a code or something off the truck to verify I'm in Limp mode?
Okay, this has been a lot and I'm more than willing to search this out. When I watched one the Youtube videos show the "Pink" wire under the fuse box under the hood was bad, I took my cover off the fuse box under the hood and there must have been 20 plus pink wires. So any help would greatly be appreciated or suggestion or reading materials. I'd really like to figure this one out, as I'm thinking something is just off.
Thanks again and look forward to being a member of the forum.
Took a measurement with the Key On, of the Pink Wire, Pin E on the connection and it never measured 12 Volts but maybe between 4 to 7 volts. I was expecting when I took this measurement, with the key in the Key on position to get pretty close to 12 Volts but no measurement has.
So here's my questions:
Can I check something on one of the fuses under the hood see if I"m at least putting out 12 Volts to the Pink , Pin E wire?
If I'm not getting 12 Volts, to the Pin E, where should I start looking back to trace the source?
It's not in limp mode, you have no 12 volts to the transmission.
Go to LT1swap.com and look at some wiring diagrams and fuse locations..
Cut the wire off and add a 12 volt wire straight to the transmission to test it.
Okay, so if they ever post my other posts, after all the research, what I did was finally took the pink wire that is not connected to the connector on the trans but was coming from the truck harness and with the key on it has 12.4 Volts and with engine on had 14.1. Now this was not reconnected back to the harness so when I did reconnected it back to the harness it had almost no voltage or was all over the place in terms of readings. So I'm going to local Trans shop here and they have my jobber filled out and Friday I'll pick it up and and start the process of re-wiring the new one in. Man this is going to be a pain under the truck.
. So I'm going to local Trans shop here and they have my jobber filled out and Friday I'll pick it up and and start the process of re-wiring the new one in. Man this is going to be a pain under the truck.
I have no idea what this means.
A wire that won't hold voltage is damaged. It can have one strand left and read 14 volts but it won't carry the amperage.
so the trans store where I get parts , when I order them they call it a Jobber, so my replacement external connector will be available for pickup and install Friday. The trans is still on the car so I'll be doing it from under the truck which is doable and will be fun..
Yesterday, I replaced the external wiring harness with a new one took it for a drive and it's still not shifting. Verified 12V at Pin E. Currently the CIL light is off but my ABS light on for some reason. So I've ordered an autel diaglink so I can pull the trans codes. Is there anything else I can do test wise to see what's going on with the transmission?
Last edited by SATEXCHEVY; 04-21-2019 at 08:28 AM.
Reason: Not brake light, ABS light
Come on don't leave us hanging! What fixed it?
Sure would be nice if folks would post the fix , after all they are coming and asking for help to fix their junk
This is the excel file I used to mark what wires went form the old to the new harness
Everyone,
I'm very sorry for not getting back to you on the fix, life kind of derailed me for a little bit. But here goes.
First I had to verify that 12 volts was present.
I first verified with key on the ignition switch at the pink wire had 12V and it did.
Next I went to the Transmission fuse and verified going in and out it was giving me 12V and it did.
Next with the external transmission wiring harness disconnected , at the Pink Wire Pin E I attempted to verify 12V was present. I did both a key on and engine running test and it vacillated between 10 and 4 volts.
once I saw at the Pink wire Pin E I was not getting a solid 12V, I took a solid 12V source spliced that in and drove it around with the Scanner and still no shifting nor speed being sensed to the transmission or speed at the speedometer. What I did do was go little further up on the pink wire from the transmission connector and I could see with a volt meter I was now getting a solid 12V so I knew the wire or the pin connection itself was bad.
Next I replaced the transmission wiring harness with a new one, and verified at the Pink, Pin E wire I was getting a solid 12V both with key on and running. Hooked up the scanner , the new transmission harness to the transmission and drove it around the block. Still no shifting, nor any readings of RPMs at the speedometer when driving and the scanner still showed no speed going to the transmission.
So now I still had no shifting, but had 12V to the Pink Pin E but no speed being sensed at the gauge or transmission using the scanner to verify this. I read on several forums including this one that if there is no Speed coming from the sensor the transmission would not know how shift without it and just put it in limp mode for safety reason. There's a great 4L60E diagnosis PDF floating around the internet and on one of those pages it shows the same info about no speed present, would send the Trans into a "fail safe" mode.
Next I did the obvious and just replaced the speed sensor for a new one and test drove the truck with scanner hooked up and still no shifting and the transmission was still not getting any speed sensed either.
Next I went ahead and replaced the speed sensor wiring harness just to make sure it was not bad as well , drove it and no shifting.
So then I went the rout to verify I had continuity from the PCM port 20(LG/BLK) and 21(PU/WH) all the way back to the speed sensor connector.
So first I checked continuity form the speed sensor to the cross over connection which sits on top of the transmission and connects the connector to the PCM and had continuity.
Next I checked for continuity from the PCM port 20 and 21 to the wiring harness without being connected to the cross over connector and it had continuity.
Next I connected it all together and checked for continuity all the way back to the speed sensor and IT DID NOT have it.
Next I unplugged the cross over connector on the side that was connected to the speed sensor and IT DID HAVE continuity!
Next I plugged back in the speed sensor connector and sure enough I lost continuity again when I tested all the way to the actual speed sensor connectors. Now I knew the new speed sensor connector was not bad and that I could get continuity all the way to the crossover plug on the speed sensor side.
Next I unplugged the Speed Sensor connector on the cross over side and removed the rubber grommet , blew out the cross over port to make sure there was not debris blocking it, plugged back in the speed sensor and re-tested all the way back to the speed sensor connector and now had continuity going all the back to the PCM.
I reconnected the PCM, and all the connectors , wiring harness etc took it for a test drive and almost crapped my pants when it shifted and there was speed being sensed at the speedometer.
So here's what the fix is 1)the wiring harness to the Transmission was bad and replaced it, 2 the rubber grommet that is used to seal the connection was to thick to allow for a solid connection on the cross over plug back to the speed sensor leading to the problem of the PCM not getting any signal from it. I tried various variations on this rubber grommet but eventually settled on just leaving it out and sure enough, my speedometer was registering speed and the transmission has been shifting just fine. I tried blowing out the connector with air , cleaning it and for what ever reason it does not like that rubber grommet, so I just left that one out.
Once again I'm very sorry for not getting back sooner but if I can supply any clarification or answer questions please post and I will get back asap. Thank you guys again for all your help and support.
Connection on the right side the rubber grommet was to large and did not allow for proper connection Cross over connector that sits on top of the transmission the blue rubber grommet would not allow for proper seating of connector to allow for continuity verified with both key on and running I was getting a solid 12V on the pink wire
04-16-2019, 03:30 PM
4L60E Full rebuild, now stuck in Limp Mode, I think. 
