Timing Question 94 C3500 7.4 Dually TBI

[trcrumb]

Hi Folks,
In my Haynes repair manual it says that the EST (Electronic Spark Timing) system must be bypased prior to checking the timing. To do this there is supposed to be a single tan wire with a black stripe with a connector that should be unplugged. This connector is supposed to be either under the relay cover on the fire wall, or close to the distributor where the wire originates out of the 4 wire plug connector to the distributor (Late model HEI dual plug distributor type).
I have looked for this connector twice extensivly and have not been able to locate it. Can anyone shed any light on this subject for me? It would be greatly appreciated.
I just installed a new distributor & would like to accurately verify the timing location. The truck runs great but this still frustrates me.

Thanks
Ted

[planedude]

it should be under the black plastic cover on the firewall. Just a little plug in the end.

[trcrumb]

Just checked under the plastic relay cover on the firewall again. There is no tan wire with a black stripe. There are no connectors, just fusable links on 5 or 6 wires.
I can see a tan wire with a black stripe on the plug going into the distributor, but I will have to pull all of the plastic loom off the wire harness to trace it. I was hoping to avoid that.
Does anybody know if the C3500 is different than the C2500 or C1500?

Thanks TC

[gecko50]

I understand the later models timing cannot be set via the plug. Timing is set by the computer. You need a special timing box like from Snap On to set and verify the timing.

I would also like to know

PAE

[trcrumb]

Check out this link that I found on another automotive forum website. The 2nd follow up suggests that it is under the dash behind the glove box inside the cab. I will check this out as soon as I can. Interesting.

http://forums.vmag.com/suvsuburban06...html#followups

[acewelderman]

My 94 has the wire behind the glove box 6 inches from the computer .You wil have to remove the g box to find this wire .Remember tan wire w black stripe .Please pm me if you dont see it there.

[trcrumb]

By God I think I've found it!
It looks like this is the plug in these photos that I took & posted on the gallery here.





My timing light is broken & I need to buy another one before I can verify that this is indeed the plug, but it sure looks like it to me. It is a single tan wire with a black stripe with a connector on it. It is taped to the harness running between the blower motor & the heater core cover.

If this is it, the Haynes manual was way off for my truck!

What do you guy's think?

Ted

[acewelderman]

You got it!! mine was tucked up under way further , but its the wire you need . first ck timing w wire conected (just for referance)then disconect & set timing to 0 .(or where you want it )then reconect wire & ck timing again to see if there was a diferance. Its nice when a plan comes together!

[trcrumb]

That was it! I got a new timinig light and had to reset the timing, the trucks running like a dream! Hope this helps some of you