I have a 95 Taurus and the check engine light fades in and ...

Hello!

To begin with, are you absolutely sure that the light says "check engine", and is not a red colored oil light or temperature light? "Check engine" lights are amber colored, and do not generally fade on and off; they come on brightly and go off completely like turing a light switch on and off...

Absolutly sure its the check engine light. Could it be a trans problem. All the sensors seem to be tight and no leaks

To begin diagnosis of a "check engine" light related problem, the first step is to retrieve stored service codes from memory. The "check engine" light is a sort of generic 'something is wrong" indicator; the computer turns this light on whenever it sees a problem in the vehicle. This could be a sensor value out of normal operating range, a short or open in a powertrain related electrical circuit, or a controlled device such as a solenoid that is not responding to commands.

On this particular vehicle, to retrieve fault codes requires use of a scan tool; the light cannot be made to flash codes as in most other vehicles.

This is 95 and it does not have scan codes. Already tried that. Light only comes on with the car in drive

A 1995 model DOES have fault codes that are generated and stored whenever the "check engine" light is on; there are 2 different types. THere are KOEO (Key on/ engine off) codes that are history codes, stored in memory, and there are KOER (key on/ Engine running) codes that are generated as a result of initiating the built in self test routine in the engine controller. You need a scan tool to initiate the self test routine and to retrive either type of service code from memory. To begin diagnosis of this type of problem, you will need to either obtain a compatible scan tool to retrieve the stored codes, or visit a shop with a compatible scan tool to have he codes retrieved before you can proceed much farther. Untill you run the KOER test sequence and retrieve both sets of service codes you really have no starting point for diagnosis; the problem could lie anywhere in the vehicle.

If the problem is intermittent, scan tools compatible with this vehicle's control systems also have a test mode called "wiggle mode" that is used to check for poor electrical connections or intermittent electrical faults; to use this the scan tool is placed into "wiggle mode" and the technician then proceeds to move wiring harnesses and wiggle electrical connectors; the scan tool beeps and stores related fault codes if a poor electrial connection is encountered.

Edited by Steve7654 on May 26 2006 at 7:05am