Thread: No 1st, 3rd, or 4th...0742, 0756 Codes

Dave,
I'm gonna go ahead and gear this question towards you.

I just finished up putting my tranny back together lastnight and tested it out. The transmission sounds normal, no whining or metal sounds.

I have Forward and Reverse.

I only seem to have 2nd gear, no matter what position the gear selector is in.

No codes came on until 15 minutes of driving while I was changing the gear selector to see if I could get the car to shift into 3rd. Once the codes did show up, here is what I got.
0742 - TCC System Stuck on. I did install the new Sonnax valve with the teflon seal, but the converter didn't stick until the tranny temp reached 225* and I was 30 minutes into the drive.

0756 - 2-3 shift solenoid valve - Performance (No First or Second Gear)
I think this is the problem. I installed 2 new shift solenoids in the valve body. I believe they are the 1-2 & 2-3 shift solenoids. But at the same time, I changed the wiring harness as well because on of the retainer clips broke, so I used one of my old harnesses.

So I think my problem is in the internal wiring harness that I changed. Because 1, of the 2-3 shift solenoid issue and 2, my performance shift light cuts off when I put the car in 4th or 3rd gear, but comes on when the car is in Neutral or Park....weird.

Dave, Do you have any other suggestions or things I can try? Is there any pinouts on the big tranny plug I can ohm out or check? Is my thinking right with the 2-3 shift solenoid?

Wow sorry to hear! The first thing I would check is to make sure the grounds are good, the ones that go to the lower front bellhousing bolt/stud. Then I would disconnect the pcm and start checking solenoid resistance right at the pcm. The shift solenoids and tcc solenoid share a common 12v ignition wire so you will need to unhook the battery and pull the trans fuse and measure from the fuse terminal in the fuse block- between that and each solenoid wire on the pcm connector. This is the best way to check as it will give you the resistance across all of the wiring. If there is an open circuit then you can back track until you find it. You can check the pins on the trans connector also. If you do this first then you can at least verify that the the solenoids do have resistance at the trans connector because if they dont you will have to go back into the trans. You can access all of this by lowering the cradle on the drivers side and removing the side cover-just what you want to do I know

Originally Posted by Trannyman95

Wow sorry to hear! The first thing I would check is to make sure the grounds are good, the ones that go to the lower front bellhousing bolt/stud. Then I would disconnect the pcm and start checking solenoid resistance right at the pcm. The shift solenoids and tcc solenoid share a common 12v ignition wire so you will need to unhook the battery and pull the trans fuse and measure from the fuse terminal in the fuse block- between that and each solenoid wire on the pcm connector. This is the best way to check as it will give you the resistance across all of the wiring. If there is an open circuit then you can back track until you find it. You can check the pins on the trans connector also. If you do this first then you can at least verify that the the solenoids do have resistance at the trans connector because if they dont you will have to go back into the trans. You can access all of this by lowering the cradle on the drivers side and removing the side cover-just what you want to do I know

There are 3 grounds that are on this stud. 1 is like a 4 gauge wire and the other 2 are about 10 gauge wire. I think you are talking about the 2 10gauge wires correct?

Checking resistance, do you know what the ohms values are supposed to be? Ohm between the fuse block and the PCM for the solenoids will let me know if there is any break in the ignition side of the circuit to the solenoids correct. Then I gues I can check between the PCM and the trans connector.

Also if I ohm out the pins directly on the trans, that will let me check resistance throught the acutal solenoids correct?

Also, does this sound like just a shift solenoid issue? If the 2-3 shift solenoid isn't working will it cause the tranny not to have 1st, 3rd or 4th?

One thing I forgot to mention is that when the trans is in 3rd or D, If I let off the gas while the car is traveling 55mph and then step back on the gas, RPM jumps until it reaches the RPM of being engaged in 2nd gear. It does not slip and hit the rev limiter.

Which book are the wiring diagrams in? The trans manual?

The transmission uses two solenoids to command all the gears. Here is the table:

1-2 on, 2-3 on -> 1st
1-2 off, 2-3 on -> 2nd
1-2 off, 2-3 off -> 3rd
1-2 on, 2-3 off -> 4th

I can't think of any one solenoid causing your problem. If 2-3 didn't work, you wouldn't have second but you say you do. But, if the other solenoid was the problem then you could still use third.

I dunno, maybe this will help.

Originally Posted by Sabrewings

The transmission uses two solenoids to command all the gears. Here is the table:

1-2 on, 2-3 on -> 1st
1-2 off, 2-3 on -> 2nd
1-2 off, 2-3 off -> 3rd
1-2 on, 2-3 off -> 4th

I can't think of any one solenoid causing your problem. If 2-3 didn't work, you wouldn't have second but you say you do. But, if the other solenoid was the problem then you could still use third.

I dunno, maybe this will help.

Yeah, I got that table off the GM site yesterday. It didn't make sense to me either because I should only have 3rd and 4th if the 2-3 shift solenoid wasn't working. However, I disconnected the Main Transmission plug from the tranny and that should have given me 3rd because I cut all the power to the tranny and both solenoids would be off. I still only had second gear, no matter what I do.

I got to take the valve body back out and make sure none of the valves stuck when I put them back in and make sure there is no debris in there. I did clean the whole valve body, but something must have gotten stuck. I'll be pulling it out Sunday.

I just wanted to give an update to those of you who have been following the thread or anyone that may run into this problem.

I have officially fixed my transmission. My initial problem was I did not have 1st, 3rd, or 4th gears. I threw 2 codes listed above, and checked the wiring regarding these codes. I also unplugged the main transmission connector.

My grounds were good and power was good. NO resistance in the wires and the shift solenoids tested okay.

Disconnecting the main tranny connector should have given me 3rd gear only, but I still only had 2nd. So I had to remove the side cover and take out the valve body. Here is what I found.

The 1-2 shift solenoid valve spring was missing. I found it in the 2-3 shift valve bore. It must have rolled to that location when I had the valve body apart cleaning it and doing the sonnax upgrades. So I put it all back together and got all my gears back. Went with the JXFM converter and works great.

However I did manage to crack the side cover somehow and had a terrible tranny leak. Got that fixed this weekend too.

Thanks DAVE for all your help!

Good to hear you got it fixed James! Those side covers are VERY touch and there is one location where the molded gasket doesnt have metal all the way round the hole the is very common to crack and I torque all of the surrounding bolts before hand to lessen the risk!

Originally Posted by Trannyman95

Good to hear you got it fixed James! Those side covers are VERY touch and there is one location where the molded gasket doesnt have metal all the way round the hole the is very common to crack and I torque all of the surrounding bolts before hand to lessen the risk!

Yep...that is exactly what happened. So I did just as you stated above.
Hand tightened all the bolts by hand first, made sure the gasket was lined up and then torqued them down.