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View Full Version : Where to place my ecm?



joegreen
05-14-2015, 10:08 PM
Hello, I think that I have asked this question before but I cannot find where I posted it. Anyway school is over and now starts the install of my new wiring harness I bought. The thing holding me up is that I cannot find a place to put my ecm. Has anyone ever put it in the engine bay. Its kind of crowded behind the dash with the heating ducts and the glove box. The truck is a 1978 chevrolet k20. Thanks

fastacton
05-14-2015, 10:20 PM
They came from the factory behind the glovebox and there should still be room there (you might even be able to use a factory mount). I wouldn't put it in the engine compartment, it needs to stay dry and away from engine heat.

joegreen
05-14-2015, 11:10 PM
I think I found a spot to put it which is right above the ash tray. Now i need to find a way to mount it isolated from ground.

joegreen
05-14-2015, 11:18 PM
here is a picture of the location

joegreen
05-15-2015, 01:19 AM
Does anyone want to buy my old harness? Is it worth anything? ill post up some pics in the forsale section once i pull it out. The truck did run with the old harness its just pretty old and somewhat stiff.

joegreen
05-15-2015, 11:51 PM
well today i started putting in my new harness and i decided that i am going to mount the ecm under the seat. The harness is the perfect length to go from the firewall to under the seat in one straight line.

joegreen
05-15-2015, 11:58 PM
So I am looking for a spacer that way i can put the cover on my ecm with my zif installed. A while back someone posted in a thread saying they made some spacers. I cant find where that was said. I am looking for whoever made them. I am interested in purchasing one.

joegreen
05-16-2015, 01:45 AM
Forget the post above, I just whipped up nice little spacer.

joegreen
05-21-2015, 03:48 AM
Update: I have been working on the efi install for the past 5 days. I have been making good progress. Most of the connections are made. What's left is power to the harness, power to fuel pump, o2 sensor, map sensor relocation, and vss hookup. So far all of the wiring is zip tied and covered in that corrugated plastic sheath. I am making up new ground wires for the body and frame and motor. Also all of the harness wires are at minimum 5 inches from any spark plug wires except for the wires that plug into the distributor but those wires still don't come close to any plug wires. .

joegreen
05-23-2015, 05:24 AM
Not everything is hooked up but i did a test start. It ran decent considering the map sensor was not hooked up. I still need to buy a longer vacuum line because i relocated the map to the firewall. I added brand new grounds from the battery to engine, battery to frame, engine to frame, frame to body, and engine to body, and battery to body. Maybe a little overkill but whatever. One thing that confuses me is where the ecm gets a signal that i am cranking the vehicle. The old harness had a wire that attached to the starter but the new harness does not. Where else could the signal be coming from that i am starting the vehicle?

fastacton
05-23-2015, 06:31 AM
I don't know why they'd delete the start wire, but it's not a huge deal to not have it. The '93 and newer TBI setups don't have that wire at all. The ECM knows the engine is cranking from the distributor reference pulse but doesn't know the starter is engaged.

joegreen
05-24-2015, 04:16 AM
ok thanks.

joegreen
05-26-2015, 03:38 AM
Right now i am trying to get the laptop to connect to the trucks computer. I want to make sure that everything is working before i button it up.