So I plan on putting my PCM on top of my Battery, I have to cut out my rusted battery tray and I plan to lower the battery about a inch and put my PCM right on top, even if I didn't lower the battery it already fits. What do you think?
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09:27 PM
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phonedawgz Member
Posts: 17093 From: Green Bay, WI USA Registered: Dec 2009
Unless you place all the wires in the holes in the PCM's connector seals, they are not watertight. The outside of the PCM will also corrode.
Considering that the majority of the wires between the PCM and the engine/transmission run to the throttle body area & to the transmission connector area, the closest location that works is the stock ECM location. Adding to that it keeps the PCM inside out of the weather. So it seems to me that the most dependable place is there.
In my opinion if you want to keep the PCM under "hood" you should locate the PCM in one of the stock water resistant boxes that GM used in the late 90s on many of their full sized cars. ----- Not my pic
You may have to wack off the corners of the PCM's fins to to make it fit.
[This message has been edited by phonedawgz (edited 05-16-2013).]
But dont the PCM's get really hot? A friend has his in the stock location and the heat from the PCM warped the plastic of the armrest and he said it gets hot, I have read on here that people have even added a fan to keep air circulation. On my chevy 1500 truck the PCM looks like its the same and it is fully exposed under the hood, not right under an open grill but on a rainy day it gets wet with the rest of the car, I certainly plan on placing it so is doesn't get wet, but if it doesn't look like a good place I will move it to he stock location. Any one else used any fifferent areas?
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01:44 AM
IFLYR22 Member
Posts: 1775 From: Tucson, AZ. Registered: May 2007
But dont the PCM's get really hot? A friend has his in the stock location and the heat from the PCM warped the plastic of the armrest and he said it gets hot, I have read on here that people have even added a fan to keep air circulation. On my chevy 1500 truck the PCM looks like its the same and it is fully exposed under the hood, not right under an open grill but on a rainy day it gets wet with the rest of the car, I certainly plan on placing it so is doesn't get wet, but if it doesn't look like a good place I will move it to he stock location. Any one else used any fifferent areas?
Mine has been in the stock ECM location since 2001. No fan and no heat issues. So, one more vote for stock location.
Most people put it in the stock PCM location.. I'm putting mine in the engine bay under the left side vent, the stock airbox and other junk in that side is being removed.
------------------ 86 Fiero GT 4spd - (pending L67 swap: VS cam, GenV) 98 GTP - Some mods
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05:53 AM
olejoedad Member
Posts: 19735 From: Clarendon Twp., MI Registered: May 2004
The PCM in my personal 3800SC sits behind the drivers seat in a PCM tray, carefully positioned as to not block full retraction of the seat. I had to slice off the corners of the PCM fins to do this. At the time the PCM was installed here, I did not think it possible to locate it in the stock location under the console. Subsequent installs now reuse this location. Why? Its cool, dry, eliminates engine compartment clutter and hidden out of sight.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
There is no harm in mounting the PCM in the engine bay just do so with the connector end down or covered. Keep away from the exhaust obviously and mount properly. These PCM's are pretty much water tight and mounted in the fender wells of some cars with no major problems. The stock location is where most of my customers end up mounting it but a few have had no problems with alternate mounting locations I have built a few of my own with the PCM in the engine bay to allow for console mounted sub woofers and also had no problems. Dan
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DARN Cars now open with Over 30 years wiring experience between cars and trade as an avionics technician in both Canadian Air Force and civilian aviation. Over 25 years experience building and modifying cars. Over 10 years of full Fiero engine swaps and harnesses building and still going.
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09:12 AM
DimeMachine Member
Posts: 957 From: Eastern Metro, Minnesota, USA Registered: Sep 2011
I mounted mine in the plastic box it came in from the 97 bonneville in the far left corner of my trunk. it is dry, has some air, easy to access. Down side is it takes a little storage space away but I have not tried to load anything in the past 3 years that would not fit because of the pcm being in the way.
------------------ 84 NB, 3800SC, E-85, VS Cam, 3.0 Pulley, 4T65E-HD, HP Tuners, AEM Wideband, Regal GS Gauges, S-10 Brake Booster. 1/4 mile -12.15 at 111mph
The PCM gets warm, it will be much hotter in the engine bay.
That's what I keep hearing, but my GTP has had the PCM mounted not far from the exhaust crossover pipe and almost touching the hot coolant hose, its been fine for 5 years now, also it's not even really mounted well so it even gets banged around, If that's not a good torture test of the 3800 PCM I don't know what is.
------------------ 86 Fiero GT 4spd - (pending L67 swap: VS cam, GenV) 98 GTP - Some mods
[This message has been edited by sco77 (edited 05-17-2013).]
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