Timing, Tuning, and Bug Hunting

I would personally never pay admission to a junk yard, even though I do use it as an amusement park....

~KJ~

Comments inline...

Thanks Neil that's the info I was hoping for. LOL - your last comment "everything" given the history of this truck - yea my sense of it too. I will go hunting for the "tan with black tracer wire at the set timing

Elliott

Neil Nels>

Neil, NG,

I wasn't able to find any tan with black wire/disconnect at any place under the heater case (there is a wire bundle there going into the firewall - near the computer).

Am I correct that you're saying to 'open' the Tan/BLK wire between the distributor and the ECM? Someone once before posted that wire ws the "IGN Bypass (timing set)". I can access a Tan with Black wire at the computer (though I'm not trusting my wire colors to match Haynes). Someone else was discussing this wire with Doc and was intending to install a switch - seems a good idea.

I did see a Tan with black wire entering the ESC (which does not match my Haynes schematic around the ESC wires). And I hotted the open connector that was bundled at the ESC (after ohm metering it first, and voltage testing it). It turns out that connector is the fuel-pump-prime.

Elliott

Neil Nels>

I was talking about that wire. Try to follow it from the dizzy to wherever it goes. I found mine under the brake master cylinder, but mine is a FS truck. I never installed the switch. Since *no one* seamed to be able to help me, I was *sure* my engine wires were non-OE, so I was going to attach a switch. But they were just fine, and I found the quick-disconnect.

~KJ~

Not surprised that you couldn't find it... GM tended to put the set timing connecter in quite a few places, forcing one to go on a hunting expedition to find it. I'll check my Delco tune up manuals when I get to the shop and see what they say about it's location and what is the correct procedure. The Mitchell wiring diagram for your truck doesn't show the disconnect (odd) so maybe yours is a "ground the ALDL to set timing. It would be better if your truck had a tune up label to reference.

Yes, normally that -is- the procedure on Chevy trucks.

Yes, tan w/black tracer is the Ign bypass circuit from the ECM to the module.

Switch= bad, putting in your own disconnect via a set of male & female terminals would do in a pinch. But let me double check the procedure in my Delco books.

ESC and EST are not the same thing, the tan w/ black going to the ESC module won't do the job.

Now ya know...

Why would a switch be bad. A nice water proof N.C. push on/push off switch under the dash would be just as good as the water resistant quick connect.

~KJ~

Because it's one more mechanical device that can fail.

I think a switch rated for FIVE HUNDRED THOUSAND mechanical cycles is less likely to fail than a quick disconnect that might have say 70 mechanical cycles if handled gingerly. But that's just my opinion.

~KJ~

How about you disconnect it from each end, and have your wife hold on multi-meter lead on the dizzy end, and you touch the ECM end? I'd do anything besides a cut & splice, it's just so "hackish". Radio Shack doesn't carry water proof switches, I know this, I tortured myself there for a year.

~KJ~

Yup, it's D-5

Hi!

I'm thinking heat and grease would probably kill it. Might not be so bad if you put it in the cab somewhere though...

William The Guesser

I don't know why everyone doesn't believe me, but the underside of my dash is within my truck. They make petrol-derivative resistant switches (Basically all that you normally run into) and IIRC most switches have temp ratings of say 150* plus. IE, they are just as susceptible as any of the other connections within the hood. The only downside I can see is your mechanic saying "what's this?" or other derivatives of this scenario.

~KJ~