4l60e
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Teching In
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4l60e I have a 99 k1500 suburban with a 4l60e. So i just got a rebuilt 4l60e from a tranny Guy he said he tested all the electrical in the transmission when he rebuilt it. Well after it was installed it is throwing p0740 and p0785 but tranny codes and circuthe problems. He told me to unplug the tranny and cleat the connection which I did and it still throws the codes. The 740 code will come on once I go 45 MPhil. The 785 will come on after that. It will start out in 2nd gear and sometimes shift hard. Also had it go into a limp mode while driving shut it off and restarted it and it worked fine. Don't know what you do I have seen it might be the pcm or the ingition switch. The tranny Guy is positive it's a electrical issue and not the trans
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From: Ann Arbor, MI
Did he "test" the solenoids or replace them?
After 17 years it really is time to replace the solenoids.
Its either exactly what the codes say it is - a bad TCC solenoid and a bad 3-2 downshift solenoid or else the connector to the trans has a lot of corrosion.
When you remove the trans connector you should get many more codes.
You can replace all the solenoids yourself; it will be easier to splice in a new TCC solenoid than replace the entire internal harness.
Just to be sure it is not an electrical problem in the car, locate the trans fuse and using a volt meter make sure it reads more than 12V with the engine running.
After 17 years it really is time to replace the solenoids.
Its either exactly what the codes say it is - a bad TCC solenoid and a bad 3-2 downshift solenoid or else the connector to the trans has a lot of corrosion.
When you remove the trans connector you should get many more codes.
You can replace all the solenoids yourself; it will be easier to splice in a new TCC solenoid than replace the entire internal harness.
Just to be sure it is not an electrical problem in the car, locate the trans fuse and using a volt meter make sure it reads more than 12V with the engine running.
Moderator
Joined: Aug 2010
Posts: 7,323
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From: Ann Arbor, MI
Every sponsor here replaces all solenoids with brand new ones, and I'm pretty sure a brand new wiring harness. IMHO that is the correct way to rebuild a trans. They can fail or at least begin to malfunction in ways that a simple ohm-meter test will not detect.
1. First make sure you have 12V+ going to the trans by checking on the fuse.
2. Search for "4l60e solenoid kit". I see complete kits with the full internal harness for around $120. You can install it yourself from underneath the car.
1. First make sure you have 12V+ going to the trans by checking on the fuse.
2. Search for "4l60e solenoid kit". I see complete kits with the full internal harness for around $120. You can install it yourself from underneath the car.
Thread Starter
Teching In
Joined: Jan 2017
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I tested the number 20 fuse and I'm getting 13.7 volts when the vehicle is running and when the ingition is turned onot. When ingition this vehicle I found out ur had a cell phone tracker wired into the ingition which we took out. So after reading some of the gm threads it says it could be the ingition so that's going to be my next step
Teching In
Joined: Jan 2017
Posts: 2
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I have a 99 k1500 suburban with a 4l60e. So i just got a rebuilt 4l60e from a tranny Guy he said he tested all the electrical in the transmission when he rebuilt it. Well after it was installed it is throwing p0740 and p0785 but tranny codes PR company and circuthe problems. He told me to unplug the tranny and cleat the connection which I did and it still throws the codes. The 740 code will come on once I go 45 MPhil. The 785 will come on after that. It will start out in 2nd gear and sometimes shift hard. Also had it go into a limp mode while driving shut it off and restarted it and it worked fine. Don't know what you do I have seen it might be the pcm or the ingition switch. The tranny Guy is positive it's a electrical issue and not the trans
Last edited by alicechan11; Mar 22, 2017 at 12:12 AM.
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Teching In
Joined: Jan 2023
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Im having the same problem with a 2005 Silverado 1500 2wd it won’t shift out of 2nd replaced trany twice replaced ecm replacer torque converter and the truck is still not shifting out of 2nd I have waisted about 2200 for nothing has anyone solved this problem yet ?
TECH Junkie
Joined: Dec 2012
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From: Iowa
ignition switch
happens all the time with this era gm vehicles
all the power for the trans has to run through the ignition switch. I've had them check fine with a volt meter (because a volt test has no load on the circuit)
but still not work.
Change the ignition switch...viola it works perfect again.
could also be a fuse or broken wiring...but the gist is...likely no power to trans
happens all the time with this era gm vehicles
all the power for the trans has to run through the ignition switch. I've had them check fine with a volt meter (because a volt test has no load on the circuit)
but still not work.
Change the ignition switch...viola it works perfect again.
could also be a fuse or broken wiring...but the gist is...likely no power to trans
