Author Topic: Redoing Interior, What is This?  (Read 1209 times)

Offline Shaker

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Redoing Interior, What is This?
« on: April 13, 2016, 11:14:43 PM »
Hi Peoples,

I`m diving in and doing a complete new interior and will be having a few questions along the way. First off the truck is a 87 R10 with an Engine, Complete Harness, Trans from a 91 GMC.

I tried to figure out what this was sometime ago when I changed the guts but now I`m getting back into working on the truck and have come across this again.

On it states " CBD 16124355 LABEL 16126473 DELCO ELECTRONICS COPORATION "

But have a look and see if you know. I`ll have more questions to follow as I`ve seen a few others I`m not 100% on under the dash.


Offline LTZ C20

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Re: Redoing Interior, What is This?
« Reply #1 on: April 14, 2016, 01:14:25 AM »
Your link to a picture isn't working. I don't think others can view images you have hosted on a Google drive or cloud account. It has to be a picture hosting/sharing site or post directly to the forum.

A quick search on Google using the 8 digit part numbers you supplied reveals the "16124355" number could possibly be a DRAC box. It converts speed sensors signal from the speed sensor into a signal the ecm and speedo can use. Basically, the speedo and ecm speak one language and the speed sensors speaks a different language, the DRAC box is the translator. Is a fairly small plastic box with electrical plugs going to it, the box is possibly green in color?
LTZ Cheyenne C20

Offline bd

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Re: Redoing Interior, What is This?
« Reply #2 on: April 14, 2016, 01:18:34 AM »
That is a DRAC module used to process vehicle speed information from the vehicle speed sensor.

In general, the DRAC (Dynamic Ratio Adapter Controller) is post-1988 truck production.  the DRAC receives its input signal from a permanent magnet pulse generator (VSS) mounted on the transmission (2WD) or transfer case (4WD) to register output shaft rotation in pulses per mile.  DRAC output is used by the engine/transmission PCM, air core speedometer, Custom Cruise III and later iterations of cruise control, and the rear wheel anti-lock brakes (RWAL) ECU for vehicle speed reference.  The DRAC approach is virtually all electronic, relying on a stationary pulse generator.
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)