wiper slow down and headlights dimming

[DelSil]

I have a 2011 Explorer XLT and when it is raining and I have my wipers on, the wipers will slow down significantly as well as my headlights get dimmer. As I am driving a squealing sound will happen in the engine compartment and the wipers will go back to normal speed and the lights will go back to full brightness. It will then repeat itself randomly. This only happens when I have my wipers on. Took it to the dealer and they could not repeat the issue. Could this be a voltage or distributor problem or maybe the battery and/or alternator?

 

[Halwg]

It sounds like when it's raining the serpentine belt gets wet and starts slipping. Could be the belt, especially on a 4 year old car, or could be the idler pulley. I'd start with replacing the belt.

 

[DeepBlueSC]

I'm with halwg on this one. Belt is the most likely culprit. Over the years I've discovered belt dressing is a temporary solution to the very problem it creates. Try using brake cleaner as you would belt dressing to clean the belt and contact surfaces. If that doesn't help then the belt/idler need replaced.

 

[orangesoda123]

It sounds like when it's raining the serpentine belt gets wet and starts slipping. Could be the belt, especially on a 4 year old car, or could be the idler pulley. I'd start with replacing the belt.

Agreed. This will be the cheapest and easiest thing to try. If it doesn't help then its time to start looking at the other pulleys.

 

[peterk9]

I have a 2011 Explorer XLT and when it is raining and I have my wipers on, the wipers will slow down significantly as well as my headlights get dimmer. As I am driving a squealing sound will happen in the engine compartment and the wipers will go back to normal speed and the lights will go back to full brightness. It will then repeat itself randomly. This only happens when I have my wipers on. Took it to the dealer and they could not repeat the issue. Could this be a voltage or distributor problem or maybe the battery and/or alternator?

Since it only happens when the wipers are on I would think it is related not to the wipers but the weather conditions making it all the more apparent it could very well be a belt issue.

Peter

 

[Bobmbx]

Change your test conditions. Drive around with the wipers on when it isn't raining.

 

[dco43054]

Change the serpentine belt. Your alternator is slowing down.

It's a PITA to do by yourself, but can be done. I did mine.