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I will be headed up to work on my truck probably saturday. And I was thinking about trying things out in this order.
1] unplug harness from trans and see if it starts in third.
2] if it does then change out mps.
3] if that doesn't work then start testing the wiring harness.
Does that sound like a good way to go or should I try something else. Radio shack is going out of business near me and I won't be able to buy any leds to do that test. And the only transmission shop in town is the one that can't figure it out.
Excellent and logical choice. You understand it and have thought it through.
Keep us posted.
Just to make sure if it doesn't start in third with the harness unplugged then it's something wrong mechanical inside the transmission for sure and not something on my side of the truck. Cause the guy who built my transmission will only warranty it if I can prove it's something wrong inside the transmission. He is currently trying to claim it's something electrical on my end.
Just to make sure if it doesn't start in third with the harness unplugged then it's something wrong mechanical inside the transmission for sure and not something on my side of the truck. Cause the guy who built my transmission will only warranty it if I can prove it's something wrong inside the transmission. He is currently trying to claim it's something electrical on my end.
Sounds like you might have a questionable builder that wants to dump everything on you instead of figuring out why your freshly rebuilt transmission isn't shifting right.
Not sure what your budget is, but if you're going to replace the MPS (about $30) you can also get an AC Delco "kit" that has all 5 solenoids, force motor, harness, and MPS for about $130. Basically, every electrical thing inside your transmission.
Yes he claims everything is my fault even the first transmission that acted just like this. He claims that it was the MLPS [not the mps] that caused it not to shift and he claims that it's working fine in a different vehicle. Even tho I have proven to him that the mlps doesn't have anything to do with the shifting. He said he didn't change anything on the the transmission and just sold it to someone else.
I still have the transmission that just went out that I can pull parts from that shifted fine until the filter stopped up due to an improperly flushed cooler and proceeded to burn it's self up. So I won't have to buy any parts. Just have to inspect them before installing them.
But just to make sure if I pull the plug on top of the transmission and it doesn't start in third then Is it something in the valve body or that he put something together wrong? Or could it still be a stuck solenoid?
Ok pulled the wireing harness and it starts out in seccond and won't go to third. It's solid seccond no slipping or trying to shift to third putting it in 1 2 3 or D makes no difference it's all 2nd gear
Limp mode in a 4L60E is 3rd gear.
Are you sure you are in 2nd gear? Did you compare RPMs to MPH?
What RPM do you have at e.g. 50 MPH and what is your rear ratio?
I'm not doubting you, it is just very important to know for sure.
If it really is in 2nd gear, shift solenoid B seems to be stuck On.
When you pull the mps, you can check it with a volt meter. Touch a lead to each side of a switch and press the button. It helps if you have some one help. My meter has an audible setting. When you push the switch it should sound. Remember that 3 are normally open until you press the switch and 2 are normally closed.
This one tests fine but as you can see the o ring seals are missing off 3 of the switches so it couldn't work right
Could the mps still cause it to be in seccond in limp mode?
I hooked the harness back up and took it for a drive again. It starts out in what feels like first and then shifts to seccond which will run 4000 rpm at 50mph. Unless it's really starting in 2nd and going to third but it really feels like 1st to 2nd.
Pulling the shifter to 1 holds it in first and moving it to 2 let's it shift but anything past 2 makes no difference.
Both my transmission guy and the guy who put it in claim that limp mode on the 4l60e is 2nd and there is no way to change gears on it cause it is complete electric. I can't convince them otherwise. Unless maybe I drive my tahoe up there and prove it to them.
So they have both officially wrote the problem off on my end and ain't gonna help with anything.
Do I need to tear into the valve body or what would be the next logical step in this process?
Limp mode is 3rd gear and if you're turning 4000 at 50 mph its gotta be in 2nd gear unless your running 4.56 gears in it. I believe that if its in limp mode it won't shift at all, and it shouldn't matter where the selector is it'd always be in 3rd gear.
First, limp mode on the 4L60E is absolutely 3rd gear, not 2nd gear.
Lots of trans guys make this mistake, partly because limp mode on a 4L80E is 2nd gear.
Easy to confirm in the following table from the GM tech manual. When both solenoids are OFF, i.e. disconnected, the trans is in 3rd gear.
At 50mph I'm sitting at a little over 3000 normal at 65 I run right around 2000
shifts to second which will run 4000 rpm at 50mph
The first quote numbers are a bit inconsistent as it puts it somewhere between 2nd and 3rd gear. If 65mph is more like 2100 with the converter locked and perhaps 2400 with the converter unlocked, then "At 50mph I'm sitting at a little over 3000" sounds more like 3rd gear.
Your second quote sounds right for 2nd gear and is more evidence that when you disconnect the trans you are indeed in 3rd gear, i.e. limp mode.
The first quote numbers are a bit inconsistent as it puts it somewhere between 2nd and 3rd gear. If 65mph is more like 2100 with the converter locked and perhaps 2400 with the converter unlocked, then "At 50mph I'm sitting at a little over 3000" sounds more like 3rd gear.
Your second quote sounds right for 2nd gear and is more evidence that when you disconnect the trans you are indeed in 3rd gear, i.e. limp mode.
I messed up when I said it was 4000 at 50 while the harness was connected. I re drove it to test and It was just over 3000. Around 3100 or 3200. And as for under 2 at 65 normal is just a guess I remember it being close to 2 while driving highway.
OK, you've now driven your car with and without the connector attached to the trans.
Sounds like you think it goes up to 2nd gear with the connector and that is the same gear you have when the connector is disconnected. Very strange.
A stuck Solenoid B would give you those symptoms - shift fine from 1-2 but then not into 3rd. With the trans connector disconnected, the stuck solenoid still forces 2nd gear.
Were the solenoids replaced with the rebuild?
Start by replacing at least that solenoid; I suggest replacing them in pairs which also helps avoid the mistake of replacing the wrong one.
If it turns out not to be a solenoid, then I would suspect a cross leak in the VB.
This should tell you that your builder is shady.... "He said he didn't change anything on the the transmission and just sold it to someone else"....are you sure he even gave you a different transmission ?...maybe the 1 you have now was returned by someone else because it wouldn't shift.
According to my atsg manual, the manual valve can override the shift solenoids. The solenoids only control what gear you are in in D4. In the other 3 manual positions the trans sbifts hydraulically. It also says quote "If both solenoids lose power, 3rd gear only will result"
OK, you've now driven your car with and without the connector attached to the trans.
Sounds like you think it goes up to 2nd gear with the connector and that is the same gear you have when the connector is disconnected. Very strange.
A stuck Solenoid B would give you those symptoms - shift fine from 1-2 but then not into 3rd. With the trans connector disconnected, the stuck solenoid still forces 2nd gear.
Were the solenoids replaced with the rebuild?
Start by replacing at least that solenoid; I suggest replacing them in pairs which also helps avoid the mistake of replacing the wrong one.
If it turns out not to be a solenoid, then I would suspect a cross leak in the VB.
He claims they were replaced but I'm under the impression that he does as little as possible on a rebuild. I can replace them both with the ones from the transmission that was working. If that doesn't work I have a guy who will buy it off me and I'll be rid of the headache. He knows all the trouble I'm having with it so I ain't screwing him over.
According to my atsg manual, the manual valve can override the shift solenoids. The solenoids only control what gear you are in in D4. In the other 3 manual positions the trans sbifts hydraulically. It also says quote "If both solenoids lose power, 3rd gear only will result"
IMHO the ATSG 4L60E manual is a barely warmed over version of their 700R4 manual. Hence the serious error in their clutch/shift table.
Obviously in [D2] and [D3] the computer still controls the shift; the trans never shifts hydraulically.
The GM "Hydramatci 4l60-E Technician's Guide" is the authoritative reference with over 100 pages of theory, color diagrams of the hydraulic circuits, etc. There is a hydraulic diagram of most combinations of shifter position and gear.
05-25-2015, 02:09 PM
