Hey guys. On my son's 87 V10 the TH700r4 converter will not lock up. The fuse blows every time, which also goes to the gauges. When I unplug the TCC connector on the trans, the fuse holds. The 700 is supposed to be a fresh rebuild, we have just got it going. It shifts and operates fine except for no lock up. I have no idea where to start trouble shooting. I thought about just getting a TCI universal vacuum operated lock-up kit and seeing if that would work and bypass the ECM, etc. Any ideas would be greatly appreciated.
CK5
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TH700 TCC lockup blows fuse, won't lock up
- Thread starter 8point1
- Start date
Going to be cheaper and easier to fix the problem as opposed to try and work around it, especially with vacuum, which is inferior.
Get a pinout of the TCC, but I would assume that none of the wires (three?) that are in the connector, should have continuity. I would also assume that if the short is in the trans, it's a pinched or rubbed wire. With pinout, any wire that isn't a ground, shouldn't have continuity with the trans housing, nor any ground wires internal to the trans. Should be able to check that without even dropping the pan.
Get a pinout of the TCC, but I would assume that none of the wires (three?) that are in the connector, should have continuity. I would also assume that if the short is in the trans, it's a pinched or rubbed wire. With pinout, any wire that isn't a ground, shouldn't have continuity with the trans housing, nor any ground wires internal to the trans. Should be able to check that without even dropping the pan.
Great info, Thank you sir
Sorry I can't point you to a particular wiring diagram that will help you, I don't know where one resides. I'm only vaguely familiar with the auto trans setups, but I am under the impression the internal wiring changed at least once, so even if you find something, it may or may not be accurate. Greg can probably address the wiring specifics.
If it is the same, I can provide the pinout for a '91 I believe.
If it is the same, I can provide the pinout for a '91 I believe.
Should be the same from 87 to 91 in this application
Ok. Going to be away from the manual for a bit, hopefully I can get to it on Friday.
http://i13.photobucket.com/albums/a253/brentmc/7b.jpg here is a link to a good picture of the solenoid and switches, the arrow in the picture is irrelevant, it is pointing out the temperature sensor.
Sounds good. Appreciate all the help. I do not know the history of this 700, I assume it was the original trans from this 87 and rebuilt, but if it was from an 86 back truck, would the TCC wiring inside be different than an 87 up? It would not have the black stripe wire coming from ECM? ...My harness going to the TCC is the 3 wire. Also, the guy I bought the truck from is big into old hot rods, I was just thinking that it may be possible this tranny was rebuilt using a non-lock up converter. Just trying to think of other reasons for problem. Will probably end up being a short like said above. The trans was supposedly built by a guy that retired from GM who is friends with guy I bought truck from. That pin out would be much appreciated whenever you have time, no hurry, thanks again.
If this trans has been rebuilt/replaced there is no way to know what you have without pulling the pan and finding out for sure. Since you are probably headed that way anyway, might as well get it over with.
If this trans has been rebuilt/replaced there is no way to know what you have without pulling the pan and finding out for sure. Since you are probably headed that way anyway, might as well get it over with.
True, I've already had pan off one time to install drain plug kit. Did not know I had the problem then though, that was before we got the truck running. Will I be able to see TCC wiring by just dropping the pan, or will I have to remove valve body, etc.? Thanks
You will see it all once the pan and filter are removed, at least with the drain plug you should save a lot of mess
FWIW, according to the 1991 Fuel and Emissions Manual, which covers the S/T/C/K/R/V trucks (thats worse than Haynes lol) The TCC plug is wired thus for the 4.3/5/5.7L trucks under 8500GVW:
Pin A: TCC solenoid, purple wire, tied into brake switch, fed from gauge fuse.
Pin B: Tied into the 4th gear and temp switch inside the trans. Lt blue wire runs to pin C7 on the ECM
Pin C: not used
Pin D: TCC solenoid. Tied into ALDL pin F, tan/blk wire, pin A7 on the ECM.
If you haven't noticed, all GM connectors are actually labeled with number/letter (both or one or the other) you just have to look closely to see them, they are normally quite small. The truck side of the TCC connector "has" to be wired as I've described, but as mentioned, if the trans was swapped/rebuilt, all bets are off as to how the TCC plug on the trans is wired up.
Hopefully that helps. Since Greg says these are the same 1987-1991, this should help anyone in the same boat. Obviously non-ECM controlled applications are going to be different.
Pin A: TCC solenoid, purple wire, tied into brake switch, fed from gauge fuse.
Pin B: Tied into the 4th gear and temp switch inside the trans. Lt blue wire runs to pin C7 on the ECM
Pin C: not used
Pin D: TCC solenoid. Tied into ALDL pin F, tan/blk wire, pin A7 on the ECM.
If you haven't noticed, all GM connectors are actually labeled with number/letter (both or one or the other) you just have to look closely to see them, they are normally quite small. The truck side of the TCC connector "has" to be wired as I've described, but as mentioned, if the trans was swapped/rebuilt, all bets are off as to how the TCC plug on the trans is wired up.
Hopefully that helps. Since Greg says these are the same 1987-1991, this should help anyone in the same boat. Obviously non-ECM controlled applications are going to be different.
