Engine/Transmission (1994 - 1998) Check engine light???

[JBain]

Hi, I have a CHECK ENGINE light and don't know why.

Oil pressure good
Alternator voltage good
Temperature good
Runs excellent

I didn't think there was anything that could cause it. Have never seen this before this truck is rock solid.

 

[hsmith]

Hmmm, on a 12 valve ?

 

[hsmith]

Never had my scanner hooked to mine but will and see what info is available if you want me to. With no ECM I would think very little if any.

 

[MLee]

Pull the code by the three on-off key strokes with the key left on, on the third stroke. Engine off of course. Count the flashes it makes.

 

[hsmith]

Should be long followed by short flashes, ie 3 long 1 short =31. We can tell you what it refers to. Hooked up on mine and was able to monitor all basics, rpm, iat, ckp, etc. 260k and mine has never came on.

 

[JBain]

I'll try the flashes thing and see what it says. This has me baffled never thought a 12 valve would ever have a CEL and at 247K miles too.

 

[JBain]

Will I tried the flashy thing go no flashes? Are you pulling my leg? But, I did figure it out at first the voltage was close to 14 however it started to go down and the lights started getting dim. I hooked up a charger and the batteries charged just fine so it was the alternator. Replaced the alternator and everything works now and no CEL.

Thanks,