88gta305

According to the wiring diagram, the TCC is controlled by the ECM, the brake switch and a relay.
Does anyone know where the relay is, my Torque converter will not lock up.

Cheers

Richard

Apeiron

Are you sure it's a relay and not the TCC solenoid itself?

Tim Burgess

There is no relay it the TCC circuit. The coil shown in the schematic is the TCC solenoid coil.

Tim

88gta305

Thanks guys, that explains why I couldnt find it.

Cheers

Richard

KevinP92Z

The various solenoids are not that expensive (~$20-25), but you'll have to drop the pan to see which color or 4 digit coil number you have (sinceGM has about 15 or 16 different valve body wiring configurations according to the tranny book I've got, plus, of course, my 2 different 700R4's required different tcc solenoids).

It's a GM part, so I doubt you'll find it at the local discount parts place.

Here's another suggestion. If you have a little extra wire and a switch, disconnect the 4 pin connector to the driver's side of the tranny, then run +12 volts to pin A of the 4 pin connector on the side of the trans. No need to run a ground to the tranny since it is already electrically grounded. While at ~50 mph at a steady light cruise, energize the wire to provide the 12V for the TCC lockup, if you feel nothing, hear nothing change on the engine rpm, and see nothing change on the tach, then you may well have a tcc solenoid out.

If on the otherhand, there is a slight drop in rpm or it feels like the tc is trying to lock but then flares back up (just like it was unlocked), then what you may have is a blown viton o-ring at the end of the input shaft that the tc goes up over. This blown o-ring allows the fluid to bypass the tc fluid circuit and won't allow lockup.

The solution is to pull the tranny back, pull the tc, replace the o-ring, and re-install everything.

I just went through this on a 700R4 I have. Talking it over with folks like Dana @ ProBuilt led me to this.

By the way, the Viton o-ring on the input shaft is the same one as the o-ring used on the tcc solenoid assy.

------------------
KevinP92Z
92 Z28 383 SLP cam,SLP headers,SLP 2ontheLeft,Trick Flow TW heads & pistons,Edelbrock base,Accel SuperRam,52mmTB,Scat Crank & forged ConnRods,MSD 6AL,SLP convertor,Baer 13/12" Track,Moser axles,Hotchkis,Genuine GM 3.42s,SLP HD Torsen,17x9" chrome SS rims
96T/A w/SLP Ram Air,SLP 2ontheLeft, Bilsteins, Baer, Hotchkis, Genuine GM, Torsen
76 4X4 Blazer 400TPI project