LM/PM to SBEC adapter?

[ShelGame]

This may sound like a dumb question, but has anyone else ever made an adapter harness to run an LM/PM on a car with an SBEC harness?

When I updated it to SBEC, I made an adapter for the Daytona so that I could still run the car using the SMEC; for testing and because my 'baseline' cal was on the SMEC.

I have a new project car coming and plan to re-wire it for SBEC electrics as well. This will be a street car, so I can hopefully do more ECU testing with it. Obviously the SMEC adapter will work in this car, too. But, I'd like to make an LM/PM adapter so that I can do more testing on that platform.

Just curious if anyone else had ever tried that. And, what issues (if any) you ran into.

[OmniLuvr]

haven't done it, but would like too!

[cordes]

I believe that Russ K. has made an adapter or modified his harness so that he could run an LM/PM, SMEC, or SBEC. You may want to contact him about that.

[iTurbo]

That sounds really tough due to the different natures of the two harnesses. Beings that the LM/PM are two separate computers and the SMEC basically combines them into one unit...

I have converted a few cars, and even made bulkhead adapters to convert early cars to SMEC/SBEC. But an adapter to convert between LM/PM and SMEC/SBEC would be nuts. LOTS of splicing and wiring harness shortening/lengthening as needed. To convert an LM/PM harness to use SMEC/SBEC sounds like a freaking nightmare to me. And not a very practical one at that.

If running a SBEC/harness in a G-body is what you're after, I would wholly suggest using a '90-'91 G-body 2.5L TI under hood harness as a basis.

[ShelGame]

That sounds really tough due to the different natures of the two harnesses. Beings that the LM/PM are two separate computers and the SMEC basically combines them into one unit...

I have converted a few cars, and even made bulkhead adapters to convert early cars to SMEC/SBEC. But an adapter to convert between LM/PM and SMEC/SBEC would be nuts. LOTS of splicing and wiring harness shortening/lengthening as needed. To convert an LM/PM harness to use SMEC/SBEC sounds like a freaking nightmare to me. And not a very practical one at that.

If running a SBEC/harness in a G-body is what you're after, I would wholly suggest using a '90-'91 G-body 2.5L TI under hood harness as a basis.

You got it backwards. Running an SBEC on a car wired for LM/PM would be just about impossible.

I want to make an adapter to run an LM/PM on an SBEC car. Or, at least, a car converted to SBEC wiring.

It will just be a jumper harness between the LM/PM and a salvaged female 60 way from an old or broken SBEC.

Mounting the LM/PM where the SBEC goes will be tricky, of course.

[135sohc]

Talking above my head here. Take a ruined PM and LM, desolder the headers and mount them in a project box, add wires to length needed and pot the project box to protect it. The car plugs into those as normal and those come together at the other end into the 60 way plug.

[A.J.]

I made an adaptor harness to run an '85 LM/PM car on a SMEC. I have a PDF conversion in here that you might find useful: http://www.turbo-mopar.com/forums/sh...car&highlight=

[OmniLuvr]

You got it backwards. Running an SBEC on a car wired for LM/PM would be just about impossible.

I had it backwards too...

so im wondering if youll hav the same problems? at least injector harness wise?

[ShelGame]

I had it backwards too...

so im wondering if youll hav the same problems? at least injector harness wise?

Well, the SBEC is individual injector drivers; the SMEC and LM are batch fire. When I wired up my SMEC adapter, I just tied the injectors together in the adapter harness so that they would fire correctly in each bank. I plan to do the same thing for the LM/PM adapter.

That's what really makes it possible - you can 'batch' the injectors in the adapter. But, you can't go the other way; there's no way to separate the injector wires in a LM or SMEC setup. They're batched at the injector harness.

I have to use the PM from the LM setup. The PM from a SMEC won't work as they trigger the injector drivers differently (sink vs. source control).

[OmniLuvr]

hmmmm, interesting...