GMC Truck Forum banner
1 - 9 of 9 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
My 04 yukon started having a shifting issue I can't find anywhere in any forum. It will not shift to 2nd gear 1,3,4,tcc all working fine and shifting normal as they always have. I first assumed a bad shift solenoid, I found a schematic showing how the 2-3 shift circuit would close the 1-2 solenoid, I then thought maybe a broken spring in the actuator. Well today I was in a hurry to get home and on a long stretch of highway opened it up. When the speedometer hit 100 I expected it to shut down as the governor on these trucks are set at 100 mph, but it didn't it kept climbing I let off the throttle at 115 and decided I should look into why. Is it possible the transmission control module is junk? Maybe this is causing my whole issue. Anyone else ever experienced this problem or know if the transmission control module also controls the governor on these trucks?
 

·
Registered
Joined
·
2,806 Posts
No. It’s a PCM in that year. Any transmission errors would have you in limp mode, aka only 2nd and R. You have internal transmission problems.

Govner is a fuel cut based on the speed signal. So either gear/tire size is changed or it’s been tuned out. If the VSS signal or PCM was at fault it wouldn’t shift at all, and no speedo.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #3 ·
Well I've had this truck for almost 2 years tires are the same tires I bought it with and no tuning has been done since I owned it. It never had a shifting issue before and always shut down at 100 mph so that rules out tires and tune so what's next? Someone at autozone mentioned a speed sensor but the speedometer works. Are there more then 1 speed sensor that might be causing this? Also have a bad hub assembly in the front sometimes it activates the abs when I first take off from a stop. Could this be causing the issue?
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #4 ·
It seems funny to me that I never had a slip in any gear, transmission always shifted perfect then suddenly I have a major internal transmission issue and no governor at the same time. There has to be something electrical going on that's causing this. I lost 2nd gear in my silverado a few years back it slipped like crazy for a few weeks before it finally let go and then it wouldn't shift past it it was stick in first and if it shifted to 2nd it just revd like it was in neutral. What would cause the governor to not work? There has to be a connection.
 

·
Registered
Joined
·
2,806 Posts
It seems funny to me that I never had a slip in any gear, transmission always shifted perfect then suddenly I have a major internal transmission issue and no governor at the same time. There has to be something electrical going on that's causing this. I lost 2nd gear in my silverado a few years back it slipped like crazy for a few weeks before it finally let go and then it wouldn't shift past it it was stick in first and if it shifted to 2nd it just revd like it was in neutral. What would cause the governor to not work? There has to be a connection.
I’d say you’re driving. There’s only single VSS or speed sensor.
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #6 ·
Ok did an oil change today and decided to mess with the transmission issue. I pulled the fuse that powers the transmission contol module expecting if 2nd gear is gone the truck would not move. Well I have 2nd gear and only 2nd gear in drive. Reverse park neutral and 2nd would not shift as expected and sluggish to take off as expected with a vehicle in 2nd gear. So this tells me the transmission is probably mechanically fine. So something is causing it to never be able to shift to 2nd gear when everything is operating as it should, transmission control module powered. Is it possible the programming has become corrupt? I read another post the guy was having a similar issue a d after replacing the trans the problem continued and it ended up being his control module had lost its programming. I think his was stuck in 1st though not sure. Just don't want to start throwing money at this thing. New rebuilt trans is $625 I'd be pissed if I bought one and installed it myself just to have the same issue. Any advise worth reading would be helpful.
 

·
Registered
Joined
·
2,806 Posts
Ok did an oil change today and decided to mess with the transmission issue. I pulled the fuse that powers the transmission contol module expecting if 2nd gear is gone the truck would not move. Well I have 2nd gear and only 2nd gear in drive. Reverse park neutral and 2nd would not shift as expected and sluggish to take off as expected with a vehicle in 2nd gear. So this tells me the transmission is probably mechanically fine. So something is causing it to never be able to shift to 2nd gear when everything is operating as it should, transmission control module powered. Is it possible the programming has become corrupt? I read another post the guy was having a similar issue a d after replacing the trans the problem continued and it ended up being his control module had lost its programming. I think his was stuck in 1st though not sure. Just don't want to start throwing money at this thing. New rebuilt trans is $625 I'd be pissed if I bought one and installed it myself just to have the same issue. Any advise worth reading would be helpful.
What fuse is that TCM?

And also where are you getting, or trusting $625 rebuilds?
 

·
Registered
Joined
·
5 Posts
Discussion Starter · #8 ·
It's the ignition 0 fuse in the inside fuse box. As for the transmission I have not gotten 1 for this truck but I have a transmission in my silverado from the same company and it's going strong 50,000 miles later. They rebuild transmissions with an upgraded kit. It takes care of all the 4l60e transmission issues and they charge like 450 for the core if you keep it. With this transmission I don't think I need one the 2nd gear works well if no power is applied to the transmission. Seems like maybe the "A" solenoid is being powered when it should be off. The shift to 3rd sends fluid against the opposite end of the "A" solenoid closing the valve hydraulically so the shift to 3rd makes sence but the "A" solenoid being powered all the time does not. Unless the module is sending power all the time.
 

·
Registered
Joined
·
2,806 Posts
It's the ignition 0 fuse in the inside fuse box. As for the transmission I have not gotten 1 for this truck but I have a transmission in my silverado from the same company and it's going strong 50,000 miles later. They rebuild transmissions with an upgraded kit. It takes care of all the 4l60e transmission issues and they charge like 450 for the core if you keep it. With this transmission I don't think I need one the 2nd gear works well if no power is applied to the transmission. Seems like maybe the "A" solenoid is being powered when it should be off. The shift to 3rd sends fluid against the opposite end of the "A" solenoid closing the valve hydraulically so the shift to 3rd makes sence but the "A" solenoid being powered all the time does not. Unless the module is sending power all the time.
ING 0 is key on for the 2-3 servos, not a TCM.

I’m trying my hardest here, but you are very hard headed. You explained the issues with your trans once again, and even stated a knowledge of hydraulics. So maybe, since everything works as it should, there too much wear on the valve body or pump? Aka bleed aka internal trans problem.
 
1 - 9 of 9 Posts
Top