Chirping sound accompanied by rpm going up and down with dimming lights
have the same problem?
Friday, October 17th, 2014 AT 8:18 AM
First check for a loose serpentine belt. Best is to do that with the engine not running! If there's an external fan blade on the front of the generator, try to push that with your thumb. If you can make it spin under the belt, it's WAY too loose. Suspect the spring-loaded tensioner pulley.
A dirty belt will cause chirping too. Never use any type of belt dressing on a serpentine belt. Dirt and debris will stick to it and cause worse slipping. The only fix for that is to remove the belt, scrub the pulleys with soap and water, then install a new belt.
The chirping implies the belt is loose, but the generator can cause noises like that too. The dimming lights tell me the generator is quitting intermittently. You can verify that by measuring the battery voltage with the engine running while the problem is occurring. It must be between 13.75 and 14.75 volts. If it drops all the way to 12.6 volts, which is what a good battery will read if it's fully-charged and the engine is off, the most common suspect is worn brushes inside the generator. Ford finally went to a real nice generator design during the '90s, second only to Chrysler's from the last 40 years, but around 2000 the engineers screwed it up again. Yours still uses the externally-mounted voltage regulator with its test points and brushes, but they covered it all up so there's no access to them. They found a solution where there was no problem. You used to be able to quickly diagnose the system and often fix it without removing the generator from the engine, but now that only applies to Chryslers again. You still can buy just the voltage regulator and just the brush assembly, but you can't test anything first. Given the amount of time to disassemble the unit, then you still can't test anything, you're better of buying a rebuilt generator if the voltage test confirms it's quitting intermittently.