View Full Version : checking trouble codes how to 88 chevy

02-12-2009, 07:11 PM
How do you check trouble codes on an 88 chevy truck?
brake lights on and no speedo? i just want to check the codes if any?
I dont think its in the same spot as my dodge 05 right under the dash?
is 88 pre obd2?

02-12-2009, 07:21 PM
I do beleive it is pre obd2. Been a while since my 88 gmc, but I think I remember everything getting hooked up under the hood some where not in the cab like our tucks. I'm sure some one on here can really help you.

02-12-2009, 07:24 PM
Check the switch for the brakelights, it's on the pedal I think.
Speedo is likely the cable.

02-12-2009, 07:52 PM
Find your Assembly Line Diagnostic Link (ALDL), lower dash area. Jumper the 2 top right holes then turn the keyswitch On.
Look at the Check Engine light...you should get a single then double flash, One then Two flashes...Code 12 which is the way for the computer to let you know "we're in diagnostic mode".
Watch for similiar flashes and write them down. When it's through reporting codes, it'll do the code 12 again.

02-13-2009, 05:36 AM
thanks clunk, i had an 82 vette that worked like that.

02-13-2009, 06:55 AM
i checked the aldl. i got nothing. I remember doing this now. But none of the ecm stuff is really hooked up to the motor. I went with w 77 motor and an hei. My main deal is no speedo and its electronic in the truck. Tim h sent me an email or two. But still no go. I can not get codes to flash. i would think the ecm is still hooked up it should flash??
who knows.

02-13-2009, 08:42 AM
On the ADL two pins you will need to find a diagram , jump A & E. Once it starts flashing count the long flash followed by the short flashes. The number you come up with go to this site to find what it is.


02-13-2009, 08:27 PM
Does the Check Engine light come on for a second after you turn the keyswitch just before starting the engine?

02-13-2009, 09:04 PM
nope, no check engine light on even then....