Re: RE: Re: Cold Starts causes Check Engine Light + LIMP mode

From: rws (rwsam2002@yahoo.com)
Date: Thu Sep 13 2007 - 16:20:11 EDT


Hi WiLieR,

On my 94 there is a thick wire bundle that is visible
on the passenger side FI's and it runs to the rear
firewall and then to the PCM. On the front it branches
over to the other bank of FI's. It's about 1" thick.
 It's wrapped in tape and covered in corrugated
plastic split-tubing. Btw, it's cloth tape. I had to
replace some of it here and there due to deterioration
and exposing the wires. I used black electricians
tape and the same corrugated tubing, but more of it to
cover the parts of the harness that was not covered.
Shame that the newer models haven't improved.

Are the copper rings you mention inside the thick
bundle? What holds the copper rings together? Are
they Ring lugs like what I see used for grounding to
sheet metal on the fire walls?

Ron

======================
When I dug into the wiring harness on my 96 I found
the fi splices to
be nothing more than a taped up copper ring that was
crimped flat onto
the stripped ends of the wiring for the injectors.
There was no
solder at all on them. I removed the rings, cleaned
everything with
electrical contact cleaner and then soldered them up
with acid-free
solder. Some more tape and things were good again.
About a month
later I was having other sensor issues so I did the
same for the tps,
map and crank pos sensor voltage feed splices and
found the same
crimped on copper rings that had corroded like crazy.
Same fix for
them and immediately saw voltage readings from the
sensors jump up to
normal. The pcm, which I had forgotten to reset after
the fix, saw it
too and threw a bunch of codes. All of the codes
basically said
"voltage reading higher than expected from tps, map
and crank pos."
Reset the pcm and it was back to smooth cold starts
and even better
acceleration. I know it seems odd that corroded wiring
would only
affect cold start ups, but that was the case with my
96.

WiLieR

On 9/13/07, Bernd D. Ratsch <bernd@dodgetrucks.org>
wrote:
>
> The splices are a solder joint - no connector unless
specified in the wiring
> diagrams. I'll pull down the wiring diagrams for you
and email them. You
> can pierce the harness if you really need to, but
it's better to back probe
> the connectors to prevent any possible corrosion
from the wire pierce (or
> you can seal it up with RTV). On the injectors -
they are ground switched -
> The ASD relay powers them up and the ground
switching is controlled via the
> PCM.
>
> If the vehicle is running rough on initial start but
no problems at normal
> temp...it doesn't sound like a wiring issue (not
ruling it out though). Do
> you have access to a scanner? If you have a DVOM
(Digital Volt/Ohm Meter),
> check the resistance of the coolant temp sensor when
cold and when it's at
> normal temp. Let me know what you find.
>
> - Bernd

       
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