2003 Mitsubishi Eclipse Speedometer reads over 140 mph with

KASTNERR

MEMBER
2003 MITSUBISHI ECLIPSE
4 CYL
FWD
AUTOMATIC
50,220 MILES

2003 Mitsubishi Eclipse will not run. I recenly replaced a head gasket on this car. When I put a code reader on the vehicle, there are no codes to read. With the reader plugged in, the speedometer will go above 140 mph and the odometer will turn miles over at a pretty fast rate. If I unplug the reader the speedometer will go to 0 mph and the odometer will stop adding miles on. What could cause this problem?

3 Replies

KHLOW2008

MECHANIC
41,814 POSTS

Hi kastnerr,

Thank you for the donation.

The only reason I can think of for the symptoms described is that the code reader used is not compatible or the PCM is not properly grounded.

If the code reader was working correctly prior to head gasket replacement, check the PCM ground at upper rear of engine.

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Thursday, January 15th, 2009 AT 2:38 PM

KASTNERR

MEMBER
2 POSTS

Can you tell me where at the upper rear of the engine that grounding of the PCM should be? Is it near a particular component or is it part of the battery ground. Or is it different on each model? Any direction would be a big help. Thanks kastnerr.

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Thursday, January 15th, 2009 AT 3:45 PM

KHLOW2008

MECHANIC
41,814 POSTS

Hi kastnerr,

Sorry I could not find any diagrams to show you the location. It should be below the distributor.

If you are unable to find any, check the injector wireharness for grounding terminals, should abe a few wires bunched into a connector for tightening to a grounding point.

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Thursday, January 15th, 2009 AT 4:02 PM