No 1st gear from a dig
Thread Starter
On The Tree
Joined: Sep 2015
Posts: 159
Likes: 0
From: Cullman, Alabama
No 1st gear from a dig I've looked a good bit for the answer to my problem and can't seem to find anyone else that has had this problem. At a dead stop, my car will not get above 2,000 rpm even if I power brake it with my foot to the floor. If I pull it into 1, it does the same thing but once I get off the line, it shifts down into 1st and starts spinning. It's like it starts off in 2nd gear no matter what and then shifts into 1st once it gets going. It's a built 4l60e and a 3800 stall. Both from PTC. If this is the converter that is bad then I'm probably going to have to get another converter somewhere else because this will make the 3rd time in 6 months that it's had to be rebuilt. Last time the lock up clutch went bad after a month of normal driving. Anyone that has any suggestions or thinks they know the answer please respond
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Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
Stating that you have had the converter rebuilt 3 times hints that something is fundamentally wrong with the converter or the trans.
Not being able to foot-brake a 3800 converter does indicate a bad converter.
If you trans is really starting in 2nd and then downshifting to 1st, that is very unusual.
A bad manifold pressure switch can cause strange shifting as if the shifter is in the wrong position and even moving around. A good scanner could diagnose this by indicating what gear the PCM thinks the shifter is in.
So, I'm currently thinking you have two unrelated problems.
Not being able to foot-brake a 3800 converter does indicate a bad converter.
If you trans is really starting in 2nd and then downshifting to 1st, that is very unusual.
A bad manifold pressure switch can cause strange shifting as if the shifter is in the wrong position and even moving around. A good scanner could diagnose this by indicating what gear the PCM thinks the shifter is in.
So, I'm currently thinking you have two unrelated problems.
Thread Starter
On The Tree
Joined: Sep 2015
Posts: 159
Likes: 0
From: Cullman, Alabama
Stating that you have had the converter rebuilt 3 times hints that something is fundamentally wrong with the converter or the trans.
Not being able to foot-brake a 3800 converter does indicate a bad converter.
If you trans is really starting in 2nd and then downshifting to 1st, that is very unusual.
A bad manifold pressure switch can cause strange shifting as if the shifter is in the wrong position and even moving around. A good scanner could diagnose this by indicating what gear the PCM thinks the shifter is in.
So, I'm currently thinking you have two unrelated problems.
Not being able to foot-brake a 3800 converter does indicate a bad converter.
If you trans is really starting in 2nd and then downshifting to 1st, that is very unusual.
A bad manifold pressure switch can cause strange shifting as if the shifter is in the wrong position and even moving around. A good scanner could diagnose this by indicating what gear the PCM thinks the shifter is in.
So, I'm currently thinking you have two unrelated problems.
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
Pure speculation here, but if the converter clutch was failing, it could have thrown off some material that ended up clogging a hydraulic circuit. Someone more knowledgeable could perhaps identify whether there is a particular circuit that if clogged, would result in such behavior. Just something to keep in mind given the converter problems you've had.
Last edited by RevGTO; Jan 14, 2017 at 09:13 PM.
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
Good point that the TCC clutch material may have clogged something.
The Solenoid have tiny filters that are easily clogged.
Looking at the hydraulics the only difference I see between 1st and 2nd is the position of the 1-2 shift valve controlled by Solenoid A, which needs to be ON for 1st gear.
However if Solenoid A were stuck OFF, you also would not have 4th gear.
I still suggest a good scan and further diagnostics to determine the likely problem. If you prefer to throw inexpensive parts at it, you could drop the pan and replace the manifold pressure switch ($35) and the two shift solenoids ($12 each). No guarantee and perhaps even only a 25% chance it fixes the problem, but I know some people find the idea of taking the car to a trans shop or finding the proper scanner to be undesirable.
The Solenoid have tiny filters that are easily clogged.
Looking at the hydraulics the only difference I see between 1st and 2nd is the position of the 1-2 shift valve controlled by Solenoid A, which needs to be ON for 1st gear.
However if Solenoid A were stuck OFF, you also would not have 4th gear.
I still suggest a good scan and further diagnostics to determine the likely problem. If you prefer to throw inexpensive parts at it, you could drop the pan and replace the manifold pressure switch ($35) and the two shift solenoids ($12 each). No guarantee and perhaps even only a 25% chance it fixes the problem, but I know some people find the idea of taking the car to a trans shop or finding the proper scanner to be undesirable.
