I had a similar problem too when my cooling fans would turn on. My RPM would jump by about 1K when both were on. When I rewired that circuit to get power directly from the battery and not the main harness, the problem went away. In your case, cleaning the grounds and main power terminals will probably fix it. Remove the wall behind the rear shelf. There is the main power terminal and ground for most of the car behind there. Clean both of these and the other ends inside the engine compartment. While you are at it, it's best to clean the other major ground and positive points between there and the battery. Chris VIN 4099 At 06:08 PM 3/1/2007 +0000, you wrote: >Hi All, > >I am looking for some advise on my rev counter problem.. > >When I run the car the rev counter works correctly... > >I then switch on the air conditioning switch to either 'max' or >heater and it still works ok.. > >However as soon as I then switch on the fan the counter leaps up by >a couple of thousand RPM (The engine does not actually change by >this amount) and the counter then leaps about with a mind of its >own !! > >Obviously some electrical problem but not sure where to start ?? > >Regards > >john. [Non-text portions of this message have been removed] To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnews Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/