What is this connector for? (1992 5.7 C2500)

[Illbedipped]

I'm stumped and cannot find what this single-wire connector is supposed to be connected to. Any help would be appreciated. The truck starts and drives fine, but has a slight misfire once in a while after it's warmed up so this wire can't be too darned important.

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[GrimsterGMC]

That looks like the tan coloured one you disconnect to set your base timing so that the ecu doesn't keep readjusting it. Once the timing is set you plug it back together and the ecu takes over the timing adjustments as required. There should be another close by that plugs into it.

 

[PlayingWithTBI]

That looks like the tan coloured one you disconnect to set your base timing so that the ecu doesn't keep readjusting it. Once the timing is set you plug it back together and the ecu takes over the timing adjustments as required. There should be another close by that plugs into it.

^^^This - maybe. Is the wire black and tan?

Here's an example of the EST connector. The other piece may be buried inside the wire loom.

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[Illbedipped]

Thanks, both of you...I will look a little more for the other end of the connector. Maybe this will give my truck a little more performance too!

 

[Illbedipped]

On further close-up inspection, the wire is PURPLE, not the tan one. The search continues.

Thanks, both of you...I will look a little more for the other end of the connector. Maybe this will give my truck a little more performance too!

One schematic I found mentions a PPL/White (430) reference wire going to the ECM.

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[Illbedipped]

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Here is a closer photo. It's a single wire round connector. I can find nothing else disconnected. I found this while checking over the TBI connections from the control module.

 

[packer0440]

It kind of looks like the oxygen sensor pigtail, but I think there is another connection around there that uses an identical connector. I'm not sure why it's there (maybe so the harness can be separated?), but it doesn't plug right into a sensor, there will just be a male connector that hooks up to it and goes elsewhere. Maybe open up the wire loom a bit?

 

[PlayingWithTBI]

IIRC the Knock Sensor wire is purple too.