RFmaster

This is a multipart question and pertains to TCC control and 4th gear indication in 7747/ 8746 or 16136965 TBI equipped vehicles.

According to one chart, ECM Pin A7, A/T TCC control (Tan-Black) is high (+12 Volts ) when TCC is NOT engaged. When TCC is commanded to lock by ECM this line is pulled low (to about 0.6 volts or there about). Can some one confirm this?? On a more technical side – how much current ECM can sink on this line??? Can logic states be reversed through setting a bit in EPROM and which one?

Similarly, 4th gear indicator line, ECM Pin C7 (Lt-Blue) is pulled internally by ECM to +12 volt rail (is this right?). When 700R4 engages into 4th gear transmission switch pulls this line low to about 0 volts.

In grand scheme of things my 700R4 is equipped with TCI 376600 Universal wiring kit which is used in non ECM controlled applications. Original transmission wiring is long gone and now I am trying to adapt existing TCI 376600 wiring to ECM with some relays or solid state switches.

//RF

RBob

iTrader: (1)

On the three named ECMs the TCC output driver is doubled up. IIRC it was a 240 mA per driver, then heat dissapation. The output logic (1 or 0) can not be set in the stock code. The output is driven low to lock the converter.

The 4th gear indicator input on the 7747 & 8746 is option bit selectable for N.O. or a N.C. switch. Not sure about the ''6965 ECM, although it probably is.

RBob.

RFmaster

Bob

Thanks for reply and confirming my initial thoughts on ECM setup for sinking 12 volt TCC switch (relay). This is what I am going to put together for my install - one additional (low current) relay to make TCC work in all gears.

//RF