4l60e not shifting higher than second
Thread Starter
Teching In
Joined: Sep 2015
Posts: 14
Likes: 0
4l60e not shifting higher than second I had recently done an LS swap into my '86 Chevy pickup. After getting it up and moving around, I decided to pull the harness and simplify it using LT1Swap's Pinout chart for the DBW harness. It's a 2003 harness, and it is DBW. I have looked over that pinout chart, the pinouts for the trans plug, the Neutral Safety switch plugs, and the VSS wire.
Using the LT1Swap wiring diagram Circuit Numbers to the PCM, the only circuits I cannot find where they go to are 1786 (ORN/BLK - Park/Neutral Signal), 1737 (YEL - Output - Park/Neutral), and 275 (LT GRN - Output - Park)
I've looked over everything multiple times, and there aren't any wires that have been removed out of the harness, that were not called to be pulled out.
The only symptoms I have are that it does not shift from 2nd gear once it is in second. When I start it, it begins in 1st, then it will shift to 2nd. But if I come to a stop, it will not shift back down to first. and under no circumstances will it shift to 3rd or 4th. if I mash the pedal, it will not kick down a gear, either. The fluid smells fine, and looks fine. fluid level is fine as well.
Any help is appreciated. I really don't want to drop $700 on a stand alone harness. and trying to find someone who will sell just a harness is almost impossible. Even the yards don't do it.
Using the LT1Swap wiring diagram Circuit Numbers to the PCM, the only circuits I cannot find where they go to are 1786 (ORN/BLK - Park/Neutral Signal), 1737 (YEL - Output - Park/Neutral), and 275 (LT GRN - Output - Park)
I've looked over everything multiple times, and there aren't any wires that have been removed out of the harness, that were not called to be pulled out.
The only symptoms I have are that it does not shift from 2nd gear once it is in second. When I start it, it begins in 1st, then it will shift to 2nd. But if I come to a stop, it will not shift back down to first. and under no circumstances will it shift to 3rd or 4th. if I mash the pedal, it will not kick down a gear, either. The fluid smells fine, and looks fine. fluid level is fine as well.
Any help is appreciated. I really don't want to drop $700 on a stand alone harness. and trying to find someone who will sell just a harness is almost impossible. Even the yards don't do it.
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
The trans shifting is controlled by the PCM. You need to connect a scanner that shows the PCM's commanded gear, and ideally, lets you force the trans into any gear.
You might have a wiring problem from pins N, P and R which allow the Manifold Pressure Switch to tell the PCM which position the shifter is in. The PCM might think you are in [D2] when you really are in [OD]. A good scanner will show that too.
These links might help you:
https://ls1tech.com/forums/automatic...lems-help.html Post #4
http://www.msgpio.com/manuals/mshift/wiring.html
You might have a wiring problem from pins N, P and R which allow the Manifold Pressure Switch to tell the PCM which position the shifter is in. The PCM might think you are in [D2] when you really are in [OD]. A good scanner will show that too.
These links might help you:
https://ls1tech.com/forums/automatic...lems-help.html Post #4
http://www.msgpio.com/manuals/mshift/wiring.html
TECH Junkie
Joined: May 2012
Posts: 3,050
Likes: 716
From: Poplarville, MS
You could unplug the connector from the trans. By doing this the trans goes into failsafe mode where only third gear will work. This will verify that third gear does work and that you don’t acutely have a problem with the trans. Although I do think your problem is somewhere in the wiring. You have to start somewhere.
TECH Junkie
Joined: May 2012
Posts: 3,050
Likes: 716
From: Poplarville, MS
For the trans to shift into third gear the PCM tunes off both shift solenoids. You are doing the same thing by unplugging the big round plug on the right side. This takes the PCM and wiring out of the equation. The trans will only have reverse and third with it unplugged. If you don’t have third gear then something is not working inside of the trans. If you do have do have third gear then your problem is electrical.
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TECH Junkie
Joined: May 2012
Posts: 3,050
Likes: 716
From: Poplarville, MS
While now we know third will work if you can get the solenoids to switch. As mrvedit said you need to hook some kind of scanner up to the car and see what the trans is being commanded to do. I have a wiring diagram for a 02 fbody but not a 03 truck. Finding where those three wires go and hooking them up may solve the problem.
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