Engine idles high and the check engine light is on - Maintenance & Troubleshooting discussion in Forkliftaction's forums

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Engine idles high and the check engine light is on

Cat Lift Trucks GC25K OR GP25K

I have a Caterpillar GC25 that when started up idles down to normal until the self test is complete (all of the lights on the dashboard go out) Then the idle speed raises and the check engine light comes on. Due to the lack of computer program and cables and after all the trobleshooting we could do without it, we have swapped most of the fuel system components from a known working unit and have had no luck solving this problem. Has anyone else run into a similar problem on this unit?

Posted 19 Jun 2009 05:41
By brett_g
joined 19 Jun'09 - 1 message
Texas, United States

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Too cool Ed. I missed that. I would asume you are right.

Posted 14 Aug 2009 11:55
By proshadetree
joined 23 Feb'06 - 484 messages
Tennessee, United States

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actually I am betting he has a tier 2, 2004 with an 4g63 or 4g64, (the dash lights not going out right away is the clue), but the serial number sure would be a help.
Since I think this is an impco teir 2, I would also suggest that he disconnect the negative battery cable for about a 1/2 hour, and try it again. I am also wonderin how high the high idle is, as this trucks idle correctly at about 700 RPM but will run with the throttle body disconnected at about 500 rpm.
He may only have a stored major code, that will be cleared via a battery disconnect on this unit.
OR (my better guess) he may have an accelerator pedal sensor mal-adjustment or bad accelerator pot.

Posted 8 Aug 2009 21:55
By edward_t
joined 5 Mar'08 - 2,334 messages
South Carolina, United States

"it's not rocket surgery"

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Im betting you have a teir 1 fuel system.These units are a pain.If you could tell me where your ecm is,In frount of or behind batery I might be of some help.Also a Serial # will be of some help like 4em045 ect Dont need it all just to help ID the operating system on truck.

Posted 8 Aug 2009 21:20
Modified 8 Aug 2009 21:22 by poster
By proshadetree
joined 23 Feb'06 - 484 messages
Tennessee, United States

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