7747 ECM to 7427 PCM question re: power feed

Well, in a post yesterday I said this was my last trip to the well for now, but it looks like I was a little premature with that....

As mentioned in an earlier thread I have picked up an '88 harness that I plan to re-pin (is that the correct term?) for a 16197427 PCM . With everyone's help here I think I've finally figured my harness out and I'm ready to start the swap just as soon as the stupid, over-priced Delphi Packard Micro-Pack removal tool arrives.

Here's my question. The 7747 has two separate 12v power feeds (one on each connector) at B1 and C16. The 7427 uses only one power input, at E16. The write up at Converting from 1227747 to 16197427 Wiring diagrams and pin outs says to move B1 to E16, which is confirmed by review of the 7427 wiring diagram. But it also says to move C16 to E13, which is listed as "brake signal" on the 7427 diagram.

Is this correct, or do I just need to input 12v to E16 on the 7427?

Brian

I think the "Brake signal" is only used for a TCC unlock/lock function IIRC. If you have a manual trans or automatic with a non lockup converter, it doesn't matter.

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Originally Posted by CDeeZ

I think the "Brake signal" is only used for a TCC unlock/lock function IIRC. If you have a manual trans or automatic with a non lockup converter, it doesn't matter.

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I'm not really worried about the brake signal as I will be running a manual transmission.

Instead, my question has to do with whether the second 12v input used on the '7747 (C16) should be moved over to the brake signal pin (E13) on the '7427. Looking at the 7427 diagram it doesn't appear that a second 12v input is used and regardless E13 isn't even listed as an power input point; it just seems counter-intuitive to feed 12v into a pin that was orignally used by the PCM to receive a brake signal.

I'm sure Dave W or someone will know for sure, but looking at the diagram PPL E13 is a signal from Brake Switch when brake is applied, power is supplied to release TCC... power to brake switch is from Pink wire which is 12 volt.

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Originally Posted by EagleMark

I'm sure Dave W or someone will know for sure, but looking at the diagram PPL E13 is a signal from Brake Switch when brake is applied, power is supplied to release TCC... power to brake switch is from Pink wire which is 12 volt.

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Okay, your comments sent me in what I think is the right direction; what threw me is that I'm not used to seeing a full 12v for a signal.

According to the wiring chart the brake signal is full B+ when the brakes are NOT applied, and 0 when applied. I guess that means the torque converter won't lock up unless there is full system current to E13. But since I'll be running a manual transmission I guess it doesn't matter, so I will not be using E13 and will just run a single orange wire from my fuse block to E16.

Have I got this right?

Again, thanks for the patience; assuming I have this sorted out I think you guys have me up to speed on the hardware side of the '7747 to '7427 conversion. Again, this forum is absolutely amazing!

Brian

Quote:

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Originally Posted by belaw

Well, in a post yesterday I said this was my last trip to the well for now, but it looks like I was a little premature with that....

As mentioned in an earlier thread I have picked up an '88 harness that I plan to re-pin (is that the correct term?) for a 16197427 PCM . With everyone's help here I think I've finally figured my harness out and I'm ready to start the swap just as soon as the stupid, over-priced Delphi Packard Micro-Pack removal tool arrives.

Here's my question. The 7747 has two separate 12v power feeds (one on each connector) at B1 and C16. The 7427 uses only one power input, at E16. The write up at Converting from 1227747 to 16197427 Wiring diagrams and pin outs says to move B1 to E16, which is confirmed by review of the 7427 wiring diagram. But it also says to move C16 to E13, which is listed as "brake signal" on the 7427 diagram.

Is this correct, or do I just need to input 12v to E16 on the 7427?

Brian

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I've done several of the '7427 PCM upgrades. I've always moved pin C16 to E13. Some of the '7427 have been for TH400, did not matter, I still moved C16 to E13. I have a '7427 conversion in progress, 5 speed manual, I'm still moving pin C16 to E13. The primary reason I always move C16 to E13 is, "I don't want a battery "+" wire loose under the dash" (even if covered with shrink tubing).

dave w

I agree with dave, and I did the same thing, go ahead and pin the wire into the connector for the 427, even though you don't have a converter clutch