just started a few minutes ago seemingly right after i hit a mean speed bump, what gives?

oh yeah, its the 89.

 

is it like 5 short 1 long or 8 short 1 long? if you ground the 1 prong connector (some are behind the glove box and some are next to the parking brake/hood release.) it will tell you any RWAL codes that are tripped...

 

im not really sure about the order of the flashing, but i thought these rigs were non-computerized? what could the codes be?

 

Is it the wait to start light or brake light blinking?

I really don't know for shore but there's got to be something that desides when and when not to turn the heaters on?
I think that all first gen have the black box on the fender, it just depend on the year as what the box control? right?

Some one corect me if i'm rong just gussing really

 

if you drop the glove box down there is a controller there, it's not associated with the "computer" on the fender. it tells you codes for the RWAL.

https://www.dieseltruckresource.com/...19&postcount=2