RWAL / Brake / Cruise Wiring Problems ?

[dani]

Hello all,
Glad to find such a great site with like-minded individuals. I hope to be of help to others in the near future but unfortunately require some expertise with something that has me at a standstill (we all love these moments don't we). Any and all help would be greatly appreciated.

vehicle specs - 1990 GMC Suburban 1500 4wd SLE - 170,000 miles
(stock as far as I know - bought it used from an elderly gentleman)

I have followed several troubleshoot scenarios from the forum which have been great but include no mention of problems where I am stuck.

original problems - cruise inop and brake light on over 35 mph - code 10 (purchased vehicle this way thinking small repair -

1- tested RWAL module 6 wire harness
terminals A-C (battery voltage)
terminals A-F (no voltage - key on)

2- tested brake switch with vacuum attachment
(switch mounted towards passenger side)
pink/black stripe (battery voltage - key on - no pedal)
purple (battery voltage- key on - no pedal)



3- began chasing purple wire through harness up behind gauge cluster where
it runs into a grey plastic 6 wire box with circuit board inside - upon
inspection found board is damaged on the brake switch 12 volt side but
find no mention of it in any schematic I have found online.







pins on housing
A- purple - 12 volt comes from brake switch with vacuum attachment
B- purple/black stripe - continues in harness towards floorboard
C- purple/white stripe - continues in harness towards passenger side of dash
D- tan/white stripe - continues in harness towards floorboard
E- tan/black stripe - continues in harness towards passenger side of dash
F- tan/white stripe - feeds to instrument cluster connector

I know the board needs to be replaced but have not been able to locate a part number or how to troubleshoot the other wires attached to it so as not to damage the new one or something else.

Sorry for the long explanation - just wanted to include as much info as possible. Thank you in advance to any who choose to help out.

-Dani-