GM circuit numbering

[steve ravet]

Peter Gargano wrote:
> 
> Just wondering about the numbering scheme used for GM schematics. For example - Ignition modules to ECU use four circuits:
> 
> CKT 423    EST (Electronic Spark Control) from ECM
> CKT 424    Bypass Control from ECM (sense to ECU too)
> CKT 430    Reference to ECM once per ignition event
> CKT 453    Distributor reference earth
> 
> Where do these numbers come from?
> Is there a "standard" colouring scheme for these circuits?

When I swapped the 2.8L in my Blazer for a 5.7L I was surprised at the
number of wires that had the same circuit number and color, considering
it's a totally different engine and was 5 years newer.  The few wires
that are also on my '78 Monte Carlo also tend to match color in the same
places.  I wouldn't rely on it when swapping engines or the like, but if
there is a mismatch go ahead and double check the connection to make
sure it's right.

--steve


-- 
Steve Ravet
steve.ravet at arm.com
ARM,Inc.
www.arm.com
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