Re: Ford Ranger Check engine light - help needed
I think you have a EEC-IV system. Sounds like you have only done the KOER
test (Key On, Engine Running). If you do the KOEO test (Key On, Engine
Off), it'll tell you what the stored codes are. I'm going to guess it's EGR
As to the reason you got that 539, it sounds like you simply didn't turn off
the AC while running the KOER test.
"Danpperk" <email@example.com> wrote in message
> My 94 Ranger, 3.0 gets a check engine light often. I read the code and the
> ECM provides a code number of 539 which I my book says"Air conditioning on
> during self test". The thing is there are no performance issues with the
> truck and the AC works fine, just a nagging check engine light comes on
> after about 15 minutes of driving. Anyone seen this before or have some
> ideas what the problem might be?