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Old 07-02-2017, 07:31 PM   #1
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Default Help for 1975 200 4x4 Ingition wiring

I have a 1975 200 4x4 with the gold box on the firewall. The truck is a 392, 4speed.

First off, can someone post or tell me where to find a wiring schematic for the ignition?

Second, there is a small box of some sort on the firewall that a white wire from the ignition module goes to, and also has a vacuum hose going to it from the carburetor. I'd like to know what that box is and what it does. It is just to the passenger side of the ignition module on the firewall. I'm thinking that it must have something to do with timing since it has vacuum and hooks to the ignition module, but I'm not sure. None of the wiring diagrams I've found so far show that white wire that goes to it from the module. If this unknown box goes bad will it cause issues with cold starts?


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Old 07-02-2017, 09:49 PM   #2
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Default Re: Help for 1975 200 4x4 Ingition wiring

Factory service manuals which contain wiring diagrams, are available for purchase via the link below:


I believe the device you are asking about is known as a Deceleration Control Module. It has nothing to do with your cold starts.
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Old 07-03-2017, 07:22 AM   #3
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Default Re: Help for 1975 200 4x4 Ingition wiring

Deja vu...............

The device you refer to is an emissions device. It is a DTM module.
The white wire feeding it from the God Box is a tach signal. It does not effect engine timing. It does (or did) effect a minor adjustment to the throttle on the carb during deceleration to reduce emissions when the throttle is closed. That is what the vacuum hose does where it is connected to the carb.
This unit can be removed, in my opinion, with no deleterious effect to the trucks operation.

The Gold Box wiring is color coded.
The Red wire goes to the ignition coil (+).
The Brown wire goes to the ignition coil (-).
The Blue and Yellow wires go the the pickup module inside the distributor.

TIP: DO NOT check continuity of the blue & yellow wires with an ohmmeter as that could short out the pickup module inside the dizzy.

Wiring schematics are in the IH Service Manual CTS-2303 for the 1974 & 1975 model years trucks/Travelalls, etc.

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