greenbuggy

Ok, so I am currently confused as hell and irritated to boot...

I started with my truck with a 1227747 ECM, made an adapter to adapt a 7747 harness --> 16168625 ECM, modded the ECM to take my ostrich and am currently wondering wtf is going on..

I had the truck running but when I'd log, I'd get a constant TPS at 3.5 and CTS at -40 deg F, obviously both very wrong.

So I look a some things, come to find out that inside the 7747 pins A11-A12 are bridged and the TPS and CTS share a common ground return at the ECM. Ok, so bridge A11-A12, reinstall in truck...

Go to log, truck starts and runs, shows normal looking changing temps and tps positions, but datamaster shows 0 RPM and 0.0 Spark advance, when the truck is running! Also my fuel pump doesn't prime when I turn the key any more

Confused as hell, I change from the modified BDKC bin I was using to a virgin BBNT, same issues.

Any ideas? Anyone?

ben73

I think you need to probably double check you adaptor with the 8625 pinouts that i posted (2 documents, 4 and 3 pages) in another thread and the 7747 pinouts.. Also check that you have continuity on all pins that should be connected and test for continuity between all adjacent pins on the 7747 end of your adaptor in case your soldering is a bit messy and you have a short there.....

The common grounding between some sensors is different in the factory drawings for the 7747 vs 8625, but from memory, the 2 sensore grounds are common inside the 8625, so it shouldn't matter..

I'll look up where i grounded my sensors and post back later..

Bill usn-1

The grounds were addressed in the wiring conversion thread.
Also I mentioned the errors with the CPI chip in the TBI system.
AFAIK the BBNT and BBMT were CPI not TBI bins.

I have ran both on my TBI.

You may want to look at your other common ground IIRC it was D1 and D2 are internally tied together on the 7747.
The wiring crossover has them going to separate pins so it was not an issue for my wiring.

I'm still waiting for the Federal mail man so I can install my Moates adapter and a TBI bin.

greenbuggy

Yeah, I read about bridging D11-D12 - before I had no cts/tps, now having bridged that TPS & CTS work fine, now I've got no spark advance or RPM when logging in datamaster. I have the KS disconnected (and have since I started, haven't yet gotten that 3.9k resistor from rat shack) and set a code either way. Tonight I'll try bridging D1/D2 and see if that helps.

Also, I know that BBNT/BBMT is a CPI prom, which is why I started with a BDKC (which I believe is a TBI prom, its from a 5.7/auto) but I get the same problems with both.