A diode is the one way device; needs to be sized correctly for voltage
and current. Why not switch the plus side though and have one circuit
for everything but the PCM and one for the PCM?
Mark N
58 Chevy Suburban
58 GMC NAPCO wideside pickup
On 7/6/11 6:44 PM, Rrogers57 wrote:
> Wouldn't a small amperage fuse on either the ground or hot to the PCM and
> radio protect you from this?
>
> If not, there is an electronic device, can't think of the name of it right now
> bit it's like a resistor, that functions as a one way gate for electricity.
> Someone with more functioning brain cells than I have right now could tell you
> what it is. I have used them in the past on alternator conversions to keep the
> charging wire from back feeding into the alternator causing the engine to not
> shut off when you turn off the ignition.
>
>
> Good luck!
>
> Robert Rogers
>
> Sent from my iPhone
>
> On Jul 6, 2011, at 2:54 PM, "James Hays"<thomasind@nventure.com> wrote:
>
>> Hi Gang: Got my head spinning - need some electrical routing help.
>>
>>
>>
>> Have GM 350 with PCM Engine Controls. Installed battery electrical shut off
>> switch on the neg. side& routed a separate ground to the PCM 3 ground
> wires
>> for constant wanting constant power as needed to keep the PCM from
>> re-programming each time you start the engine.
>>
>>
>>
>> Problem is with the shut off switch open ( off ) still have ground at
> normal
>> places - engine, frame& so on. The way I look at it if I ever ( mistake )
>> try to start the engine with its heavy draw without connecting ( closing )
>> shut off switch I will cook the light weight wires in the PCM.
>>
>>
>>
>> Is there any way to have constant energy for the PCM ( and radio clock )&
>> still have a main shut off switch - like it to be neg. but would settle
> plus
>> side if it will just work without cooking stuff.
>>
>>
>>
>> Thanks,
>>
>> Jim
>>
>> 55-1st PU 5 window / 350/ 4L60E
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