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I have a 2000 Ford Focus 2.0 DOHC with a manual transmission. When my engine is hot and at an idle. It likes to go from 800rpm to 300rpm for a second. I notice the dash lights dim on the dash. It does it every time after I come to a stop. I already did a tune up to my car. Today after that happened once. A light came on the dash and It was too fast for me to see. It was red so it was not a check engine light. I tried to do a vacuum leak test but I didn’t find anything. I am wondering if it could be the battery or the alternator. I haven’t had time to test starting and charging. This has been going on for a while and I would like it to stop.
If a light comes on the dash for a split second would it save in the ECU?
Also, please post any diagnostic tests that I could do.Thanks for reading and have a happy new year.
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hopefully its the system charging light and not oil light.
sounds like the charging system is having a problem. go
to an auto part store and have the battery and alternator load tested.
its free. :cheer:That light you are seeing is probably the battery light, which tells you that your alternator isn’t working properly, however due to the low RPMs, it is not able to produce enough voltage to satisfy the sensor for just a split second and causes that light to flash. Try cleaning the Idle air control motor as it might be sticking causing the drop in RPMs.
I found out it is the voltage regulator. I still have to replace the alt. I might as well do the timing belt seeing that I have to take off the engine mount.
If you’re going to do the timing belt you must have the OTC timing tool kit. The one for the Zetec motors is only about $35. I had to get one for mine. Don’t even attempt to do the job without it, you’re just going to end up with major issues. This vid isn’t Eric but the guy did get really good video of doing this job the right way.
Are you sure it’s the alternator? Be sure to use the above videos to check it out. The reason I ask is because if the idle dips too low the battery light will come on as it does when the engine stalls. This would be normal. Personally I thought you had an idle problem reading your post. If the IAC valve is not working properly when you come to a stop it can cause a problem like that. I don’t see the alternator causing the idle problem so much as an engine performance issue causing the alternator not to spin fast enough to produce power. I’m not saying the IAC is bad, perhaps it’s getting bad info or there is some other issue causing the idle to drop that low.
Keep us posted.
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