TCC Lockup-Diagnostic Help?
#21
Race Director
Thread Starter
Have not done the FSM TC Lockup flow chart yet. But I'll most likely be home tomorrow, and if so, i'll do what I can follow from the FSM. Should I do those tests with the engine cold, or whenever the TC no longer locks?
#22
Race Director
Do your testing while it's in the failed state.
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1993C4LT1 (01-31-2018)
#23
Race Director
Thread Starter
ALDL droid was working perfect today. For the "TCC LOCK" It would say 'locked' or 'unlocked'. Also, speed and RPM were agreeing with what the car was telling me. So I knew all was well with aldl droid.
I didn't connect it to the car until I felt the converter was no longer locking. Any speed above 47 mph with light throttle load, and it would say "locked". Give it enough throttle to pass someone, or floor it, and it would read "unlocked". Also read "unlocked" when below 47 mph.
Anyways, when it said locked, I knew it wasn't. How do I know? At about 66 mph(need to look at the log to confirm, but pretty sure it was 66), I was at 2k rpm. Should be 70 mph at 2k rpm in OD with TC locked.
Also, I was doing 55 mph and dropped the shifter to 3rd. I felt it drop a gear, heard it through the exhaust and rpm increase.
I didn't connect it to the car until I felt the converter was no longer locking. Any speed above 47 mph with light throttle load, and it would say "locked". Give it enough throttle to pass someone, or floor it, and it would read "unlocked". Also read "unlocked" when below 47 mph.
Anyways, when it said locked, I knew it wasn't. How do I know? At about 66 mph(need to look at the log to confirm, but pretty sure it was 66), I was at 2k rpm. Should be 70 mph at 2k rpm in OD with TC locked.
Also, I was doing 55 mph and dropped the shifter to 3rd. I felt it drop a gear, heard it through the exhaust and rpm increase.
#24
Race Director
Thread Starter
Dumb question, if the converter was bad would it show up in the fluid? Or any obvious signs? I will the drop the pan and test the solenoid, but that is the last step before ruling anything else out. Sorry to bring the thread back.
#25
Race Director
The only obvious sign that I am aware of would be when the converter got so hot that the body turns kind of blue. Blue like when you temper steel, which is not something that happens often.
#26
Burning Brakes
Mine TCC solenoid was acting up, caused me to burn out fuses. It was still under 25 ohms, but had an internal short that would draw 10-15 amps. Not sure why I measured 25 ohms, with such a high amperage (short). There is a connector on the driver side of the 700R/4L60 to send power to the TCC and valve body.
I picked up a replacement solenoid from Rock Auto. I've seen torque converter clutches fail and cause the back of the converter to become discoloured.
I still prefer seeing a LED light on my dash showing me that there is power going to the TCC solenoid.
I picked up a replacement solenoid from Rock Auto. I've seen torque converter clutches fail and cause the back of the converter to become discoloured.
I still prefer seeing a LED light on my dash showing me that there is power going to the TCC solenoid.
Last edited by Mike Holmen; 02-11-2018 at 01:28 PM.
#27
Race Director
Thread Starter
So when your solenoid was acting up, what would the converter do? I'm not cheap, but hate spending money just to do it. What I mean is, dropping the pan, buying new fluid, filter, and the solenoid. Only to see car does the same. Anyway to see if the converter is discolored, without removing the trans
#28
Burning Brakes
It felt like I was slipping back and forth between 3rd and 4th gears, bouncing up and down. I couldn't put any power onto the throttle at all in the higher gears. Made difficult passing cars on the highway.
You just need to remove the dust shield that cover the torque converter and look at the back of the converter, that's next to the flex plate.
Honestly its not that expensive to change the transmission oil. Just buy a transmission filter replacement kit. I change mine every year, just so I can see the condition of the transmission. I just run penzo ATF, none of that pricey synthetic stuff.
The solenoid is on the driver side, near the front area. Usually there are two wires going to it. TCI makes a 4th gear TCC lock-out kit, so you can bypass the computer. My home made kit is just a fuse, manual lighted switch, and some wire. I also use a relay so when you hit the brakes it de-energize the TCC. The power is supplied by a key on power wire.
You just need to remove the dust shield that cover the torque converter and look at the back of the converter, that's next to the flex plate.
Honestly its not that expensive to change the transmission oil. Just buy a transmission filter replacement kit. I change mine every year, just so I can see the condition of the transmission. I just run penzo ATF, none of that pricey synthetic stuff.
The solenoid is on the driver side, near the front area. Usually there are two wires going to it. TCI makes a 4th gear TCC lock-out kit, so you can bypass the computer. My home made kit is just a fuse, manual lighted switch, and some wire. I also use a relay so when you hit the brakes it de-energize the TCC. The power is supplied by a key on power wire.
Last edited by Mike Holmen; 02-11-2018 at 04:36 PM.
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1993C4LT1 (02-11-2018)
#30
Race Director
Thread Starter
Got under the car to remove the torque converter dust cover. To see if it was blue, since you told me it would blue if the TC was burnt. Weird thing is, the whole TC is blue. Supposedly the stock TC was rebuilt.
I couldn't remove the whole thing because one bolt was blocked by the exhaust. I didn't feel like dropping the cat on the passenger side.
I couldn't remove the whole thing because one bolt was blocked by the exhaust. I didn't feel like dropping the cat on the passenger side.
#31
Race Director
Got under the car to remove the torque converter dust cover. To see if it was blue, since you told me it would blue if the TC was burnt. Weird thing is, the whole TC is blue. Supposedly the stock TC was rebuilt.
I couldn't remove the whole thing because one bolt was blocked by the exhaust. I didn't feel like dropping the cat on the passenger side.
I couldn't remove the whole thing because one bolt was blocked by the exhaust. I didn't feel like dropping the cat on the passenger side.
I mean blue as in it got scorching hot at some point.
If you don't see that, then consider the converter as having passed visual inspection.
Last edited by PatternDayTrader; 02-17-2018 at 07:50 PM.
#32
Race Director
It seems to me that if your problem was the converter itself, then it would be in the failed state at all times. Its not impossible you have some weird temperature related problem causing an issue with the way fluid pressure applies the converter clutch, but I would think the probability of a temp related electrical problem is much higher.
Bottom line here is you have kind of an unusual problem, and once you get it solved, I (for one) will be interested to hear about the solution.
Bottom line here is you have kind of an unusual problem, and once you get it solved, I (for one) will be interested to hear about the solution.
Last edited by PatternDayTrader; 02-17-2018 at 07:51 PM.
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1993C4LT1 (02-17-2018)
#34
Burning Brakes
You have to take the dust cover right off. You would have to take a picture looking at the engine and converter. With your converter being blue, it would have to have some heat staining, burnt bluish to pale light blue.
Just looking at that picture would make me think that converter is still working. Usually when they are smoked there is more heat discolouration. Just my opinion.
Could still be a TCC solenoid issues. Drop the pan and find out for sure.
Just looking at that picture would make me think that converter is still working. Usually when they are smoked there is more heat discolouration. Just my opinion.
Could still be a TCC solenoid issues. Drop the pan and find out for sure.
#35
Race Director
Thread Starter
Looking at a pic of a TC solenoid now, and I don't see where I would be able to get an ohm reading from. Maybe not a good enough pic? Either way, I'm going to buy one in case I do need it.
#37
Race Director
Thread Starter
Got the part like two weeks ago, or so. Gonna go see,if the Chevy dealer has the trans filter in stock. If they do, I'll start to replace it today. I'll post a pic of the TC solenoid shortly.