speedo sleeping

[coldbear]

2001 Zetec has a bad habbit. As unit is driven,hot or cold, the speedo goes back to zero and engine power is reduced 10-15 percent. Any ideas on this prob.? Alltinator changed at 80,000. miles. Current mileage is now 170,000. Thoughts?

[Sponsor]

[nilskje]

If the odometer shows only --- when this happens, its the VSS going bad, it will certainly reduce the pwr , the ECU need seed info to work properly...

[coldbear]

VSS ???? Define please.

[amc49]

vehicle speed sensor, on trans somewhere...........

[coldbear]

Thanks!

[whynotthinkwhynot]

You can test your alternator while driving. Since it went out at 80k, and now you have 150k- I'd suspect it.

Key OFF, press and hold odometer trip reset button. Turn key to ON (not ACC), continue to hold button until the odo display reads [test]. Release the button, now each time you press and release the odo reset button it will scroll through one of 30 test functions. It will remain in test mode until you turn the key off. The one you're looking for will read [bat 12.1], or whatever your battery voltage might be. Typically it is .2v lower than the reading you'd get from a meter between the battery terminals. Now, if you start the engine without turning the key off, you'll see your alternator voltage. You can monitor it while you drive in case you have problems with the voltage regulator putting out too much voltage. Anything over 14.9v is a problem. When the voltage regulator (built into the alt) dies off, you might see voltages as high as 50v from the alternator, but typically it's around 16v when things start to die off. Continued use of the alternator with over-voltage like this will cause the death of some electrical components giving you more problems to fix after the alternator goes out completely. IIRC, the battery light will come on for over-voltage problems like this once it reads over 16v.

[FocusGhia]

Same here...VSS problem.

I have this for checking battery/alternator state. Gives constant readout from cigarette lighter plug. Not sure if you guys can get it in the US.

http://www.amazon.co.uk/Display-Digi...9020332&sr=1-9

[coldbear]

That is so freakin' cool,man. I had no idea that I could do a self test on my Focus. Thanks Whynot for the great idea. I also have a meter I use in my F-450 motorhome that tells voltage, oil pressure, water temps, and MPH. I use the test read port to plug the unit in and it reads untill the key is turned off. I'll try that test tomorrow.