Check engine light

[Ontheboulder]

My 87 V2500 shows a check engine light after a few automatic down shifts while pulling a local hill. after I get home and shut it off the check engine light goes away. Any one got any ideas what might be goin on?? I think its a 700r4 transmission. thanks

 

[YakkoWarner]

First thing to do is jumper the ALDL pins and see what codes blink out. Even when the light is off, the error is stored in memory so reading the codes will tell you what error(s) - could be more than 1 - triggered the warning light.

 

[gmbellew]

total guessing here based on almost no information, but maybe the knock sensor is failing the self test. pull the codes and provide some more info.