DRAC Problem

[aussierob]

Hi there

I work for an auto trans mob in Australia

We have a customer with a 1993 3500 with 6.7l Turbo deisel with a 4L80E trans in it.
We have found the problem to be the DRAC, It does not create a pulse just earths the 5V from the ECU. thus no upshift or speedo
all other sensors etc test ok
Any one had any experience with these and info about getting them fixed or new one.

I have found lots of info on how to "program" the DRAC
but that is no help when the thing does not work.

Thanks

[aussierob]

The DRAC- Digital Ratio Adapter Control
Or Speed Buffer is its common name

[rhsub]

DRAC module is usually mounted by park brake assm
My wiring diagram shows a 9 wire plug and a 4 wire plug
__________ ______________________
[1][2][3][4] [1][2][3][4][5][6][7][8][9]

4 wire plug
1 speed signal to cruise control (convience centre) Red/white 818
2,3,4 empty

9 wire plug
1- VSS Lt green/black 822
2- Ground, Blk/wht 450
3- 12V ign, Brake fuse Brown 250
4- Speed signal to anti-lock brakes White 696
5- Empty
6- VSS Purple/white 821
7- Vehicle speed output to PCM/TCM (D2) Brown 437
8- Empty
9- Speedo output to dash Lt blue/blk 824

Hope this helps
Ron

[aussierob]

thanks but I have all that info.
and know how to test the systems involved with it, Also how it basically works.
the hard part was finding it as its a right hand drive conversion. had been moved from original position was sort of tucked up above radio unit. all our books are refering to LH drive

just what to know if there is somewhere to get them fixed (auto electronics repairer) or new unit.
anyone know a ball park cost of a new unit?
Bloody customer wants it by mid week LOL
they will buy import cars.