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TBI upgrade - ECM mounting

Mastiff

Mastiff

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Has anyone mounted their ECM under the hood? Is there any good reason not to, if you make sure to put it in a watertight enclosure? I can't find a good spot in the cab that doesn't get in the way of things, and I don't want to bury it while I'm still hacking chips. I don't think I'll ever want to bury it under the dash even if I could.
 
On the same note of mounting TBI computers, is it supposed to be isolated or if it grounds out to the truck is that ok? Trying to figure how to mount mine as well.
 
Late model ones have them mounted up under the dash forward of the glove box. When I TBI'd my '78 I put it and all sensors/relays in the glove box.
 
When burning chips I just leave mine dangling, otherwise it's bolted up like stock. If you take out the glovebox it will sit between the dash and the heater core pretty steady.

It doesn't need to be grounded.

Also, the less heat and dirt the better, confining the ECM can't help the board components with heat issues. There were some water *resistant* underhood ECM's, but those were Corvette only IIRC.
 
dyeager535 said:
When burning chips I just leave mine dangling, otherwise it's bolted up like stock. If you take out the glovebox it will sit between the dash and the heater core pretty steady.

It doesn't need to be grounded.

Also, the less heat and dirt the better, confining the ECM can't help the board components with heat issues. There were some water *resistant* underhood ECM's, but those were Corvette only IIRC.
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I guess maybe the TBI is different than the TPI. When i bought my wiring harness years ago for my TPI install it said to make sure the ECM was grounded. :confused:
 
Yeah the TBI one doesn't need grounding. it is grounded but via the loom, not the case.
 
ECM no likey the high temps that are under the hood! Find a nice dry place inside for it!
 
All the ECM's I am aware of (OBD1 GM stuff anyways) all have grounds for the ECM in the wiring harness.

In any case, the mounting style of the C/K/R/V truck ECM does not provide for the ECM case to ground to the body.
 
Wingnutt said:
ECM no likey the high temps that are under the hood! Find a nice dry place inside for it!
Click to expand...

That's the thing. I don't believe that my K5 fender gets nearly as hot as it does under the dash after the truck sits for hours outside in Yuma with the windows closed. It must be designed to work in desert heat.
 
dyeager535 said:
All the ECM's I am aware of (OBD1 GM stuff anyways) all have grounds for the ECM in the wiring harness.

In any case, the mounting style of the C/K/R/V truck ECM does not provide for the ECM case to ground to the body.
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I do remember there being a plastic housing that the ECM was originally installed in that mounted up above the glove box but when i bought my wiring harness there were only 3 wires to hook up, one for constant hot 12 volts, one for switched hot 12 volts, and another for 12 volts while cranking. There was no ground wire involved so maybe that is why they said to ground the ECM.
 
22-1.jpg


That work? In any case, you can see a few of the ECM grounds right there. The ground distribution link from that page doesn't work right now, or I'd use it. ECM grounds are integral with the 2 connectors to the ECM.

Those all ground to one of the intake bolts originally, I've got mine to one of the accessory bolt holes at the back of the passenger head.

Oh, and here is the pinout for the 1227747 ECM, you can see the system and sensor grounds at D1 and D2.

ftp://ftp.diy-efi.org/pub/gmecm/manuals/1227747/747ecm1.jpg
 
I'll also say not to put it under the hood and that it does not need grounding.

Like Dorian said, I just leave mine hanging when fooling with the chips, and it fits in a plastic inverted tray like affair.

And the ECM case is not sealed, so dirt or water can get in easily, plus it needs airflow so you can't put it in a sealed box. And the cab might reach 150+ in the summer heat, but the engine compartment sees that and more on a regular basis, not to mention the dirt and potential dousing.
 
1 word.... PROMINATOR :D :wink1: :pimp: :grin:


Don't know if the harness would reach but it would be cool to have it in the center console.
 
I mount mine under the dash against the heater box :) I take two peices of heavy duty velcro, stick it to the back of the ECM, and the heaterbox, I then mount it in such a way that the bottom access hatch of the ECM hangs out just below the bottom of the dash. That way it is just two screws, and you have direct access to the ECM without pulling anything apart. The velcro absorbs any vibrations, and even though it is sitting on a heating duct, it doesn't seem to get any warmer than sitting overtop of the heaterduct behind the glove box.

I can get pics if anyone wants a better idea of what I am talking about :)
 
beastofablaze said:
1 word.... PROMINATOR :D :wink1: :pimp: :grin:


Don't know if the harness would reach but it would be cool to have it in the center console.
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Moates ostrich blows the prominator out of the water.
 
Don't know about prominator, but the Ostrich has been working well for me, and Moates is good to deal with. I also have my ECM in place of my center console for easy access for tuning. Put it in a metal box for protection with connectors for a PC, a switch to go into diag mode, and the SES light.
 
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