P0740
Thread Starter
On The Tree
Joined: Mar 2008
Posts: 190
Likes: 0
From: Fort Worth , TX
P0740 Having issues with P0740 code. Any advice ??
This is in a 1997 Z71 Silverado with a 5.7 Vortec and 4l60E. Cannot get rid of the code. Transmission only has about 2,000 miles on the rebuild. I know the code is for TCC slip / malfunction. I had this code in the past but it would come and go. Installed a brand new converter at the time of the rebuilt transmission install. I know the symptoms are that the TCC is slipping, but the truck seems to drive just fine. Just trying to get rid of the code so that I can pass inspection.
This is a stock daily drive truck. No mods. I would like to just get rid of the code. I would just disable the code to pass inspection , but I know how limited tuning options are for the 97, I do have HP Tuners but that's not an option with out wiring up a modern PCM. Which is something I would like to avoid on a stock daily driver. I have an older TunerCat program on my old laptop from my LT1 days, but would have to buy a cable and am unsure if I could even disable this DTC with that.
Any ideas of solving this problem would be appreciated.
This is in a 1997 Z71 Silverado with a 5.7 Vortec and 4l60E. Cannot get rid of the code. Transmission only has about 2,000 miles on the rebuild. I know the code is for TCC slip / malfunction. I had this code in the past but it would come and go. Installed a brand new converter at the time of the rebuilt transmission install. I know the symptoms are that the TCC is slipping, but the truck seems to drive just fine. Just trying to get rid of the code so that I can pass inspection.
This is a stock daily drive truck. No mods. I would like to just get rid of the code. I would just disable the code to pass inspection , but I know how limited tuning options are for the 97, I do have HP Tuners but that's not an option with out wiring up a modern PCM. Which is something I would like to avoid on a stock daily driver. I have an older TunerCat program on my old laptop from my LT1 days, but would have to buy a cable and am unsure if I could even disable this DTC with that.
Any ideas of solving this problem would be appreciated.
Moderator
Joined: Aug 2010
Posts: 7,322
Likes: 528
From: Ann Arbor, MI
Please confirm that you are getting the code with both the previous and current converter - that will rule out a bad converter.
Who rebuilt the trans? How much did you pay for it? The cheap rebuilds don't bother with rebuilding the valve body (VB), using new solenoids, etc.
I currently suspect a bad TCC solenoid or leakage in the VB.
Slipping converters often give a P1870 code; did you ever get this one?
Who rebuilt the trans? How much did you pay for it? The cheap rebuilds don't bother with rebuilding the valve body (VB), using new solenoids, etc.
I currently suspect a bad TCC solenoid or leakage in the VB.
Slipping converters often give a P1870 code; did you ever get this one?
Thread Starter
On The Tree
Joined: Mar 2008
Posts: 190
Likes: 0
From: Fort Worth , TX
I had previously gotten the code occasionally, it would come and go ever so often for years. But never felt like there was anything wrong or even noticeable. Recently had transmission rebuilt, also put in brand new converter. The build is just a budget , stock style build. From local guy who I have had build several other 4L60Es in mine and friends cars. The code is constant now, can re flash and it will come back on a few minutes later.
Thanks for the reply. Was told to try changing PWM solenoid, so may start there .... Any suggestions appreciated.
Thanks for the reply. Was told to try changing PWM solenoid, so may start there .... Any suggestions appreciated.
Moderator
Joined: Aug 2010
Posts: 7,322
Likes: 528
From: Ann Arbor, MI
You certainly can start with the TCC PWM solenoid, but you might also replace the main TCC solenoid - the one held with two bolts and wired to the harness. This is easy to replace as you can purchase one which splices into the harness.
If that doesn't help, next is to replace the TCC regulator valve, but that requires removing the valve body (VB). It is possible/likely that the VB bore for that valve is worn. If it is indeed worn, you choices are:
1. Replace the valve body with a rebuilt one.
2. Sonnax makes an oversize TCC valve, but it also requires using a special (expensive) reamer and experience with it.
3. Install an inexpensive Fitzall valve which uses o-rings to seal against a worn bore. This does change the TCC operation to On/Off instead of PWM, but I doubt any performance minded person would mind - the TCC engagement is then a bit more noticeable.
If that doesn't help, next is to replace the TCC regulator valve, but that requires removing the valve body (VB). It is possible/likely that the VB bore for that valve is worn. If it is indeed worn, you choices are:
1. Replace the valve body with a rebuilt one.
2. Sonnax makes an oversize TCC valve, but it also requires using a special (expensive) reamer and experience with it.
3. Install an inexpensive Fitzall valve which uses o-rings to seal against a worn bore. This does change the TCC operation to On/Off instead of PWM, but I doubt any performance minded person would mind - the TCC engagement is then a bit more noticeable.
