MicroSquirt.com read only forum (Jan.15,2018)

Has anyone installed a MSII to convert a tbi chevy truck to multipoint and maintain the old ecm to control the transmission. Apparently you only need to maintain the tps, map, and ignition signals to the old ecm.

this page gives a little insight to it when swapping in gm tpi on a tbi motor
http://www.edgesz28.com/edgesZ28/suburb ... ronics.htm

The last step is the splices for the transmission control:

"31. 4L60E Jumpers (A,B,C):
A - Plug the MAP jumper into the original MAP plug.
B - Splice the blue wire head into the original blue wire of the TPS plug.
C - Splice the purple wire head into the purple wire with white stripe of the original distributor plug."

So the question is, when wiring up the MSII, do I just send the signal wire to the truck ecm from the MSII, or let the truck ecm power up the sensor and send the signal wire from the truck ecm to the MSII.

442olds wrote:Apparently you only need to maintain the tps, map, and ignition signals to the old ecm.

hi 442olds -

I think it also needs VSS. I lost my cruise control on the swap (4L80E) as well and it would always throw codes without the EGR wiring in-place and other issues with other stuff, so... I left everything connected to the GM ECU. Everything. I then tapped into the signal wires for the MS (GM feeding the sensors) and cut only the injector wires for MS to control. Works fine, and I can change the shift patterns without bothering MS. Well, it´s one way to do it.

David

Ok, so bascially I leave the factory wires intact, then tap the signal wires to feed the MSII. That's easy enough. That should leave the vss signal intact to the gm box too.

I'm also assuming that you left the ignition control up to the gm box. But I'm also switching to a big block, so I would like to have timing control. which really isn't a problem, just a splitting the signal from the ignition module to both computers and using the MSII to trigger the coil.

And to clear up any stray engine codes that the gm computer may spit out I can just have a chip burned with those checks turned off, like the egr.

thanks for the help.