Hey, I just picked up an 06 evo9mr and am experiencing an issue with my instrument lighting. They're steady at idle but when once the accelerator is depressed the instrument lights start to "pulse". Has anybody see this? I'm thinking goltage regulator.

 

sounds like an alternator issue.

but first, check the battery connections and the ground to the body. pull on them pretty hard because sometimes they look okay but aren't. corrosion and rust can hide pretty well.
after that, run a volt meter to the battery terminal while the car is running. make sure the alternator is putting out enough voltage.

 

Yah i would highly suspect the alternator too. You could have someone else give it some gas while you use a meter on the battery. Take those results and go from there. It could also be a component in your electrical system malfunctioning and drawing way too much power, so chasing down possible shorts etc could be warranted.

 

Second this too. Clean all battery terminals, make sure everything is tight including the various grounding points, especially those dealing with the instrument cluster (driver Kick panel i think). Basically check all the easy stuff before going deeper.

 

After all that, check any alarms, turbo timers, or boost controllers, if you have any. They are notorious for messing up electrical circuits.
If that's not it, then check anything else that's electrical and aftermarket. Stereo Equipment (especially amplifiers), Lighting, or anything else you happen to notice.

 

Ok, thanks for the info. I will check all the associated grounds first and see where it gets me. I did take a meter to the alternator and battery leads, showed steady voltage at idle then it fluctuated once i hit the gas which is what got me thinking it was an issue with the alternator.

 

how much voltage? either way, yeah.. it sounds like that's your issue. alternator swaps on our cars is a *****, though LOL

 

Lol yeah it doesn't look like a fun time at all!! But the more I look the more I'm thinking I need to get the dealer but me a new alt...

Just took some more readings....

After startup / high idle - 14.50v - 16.20v (instrument panel lights pulse)
Idle - 14.21v **steady reading** (instrument panel lights do not pulse)
Off idle - 14.40v - 16.20v (instrument panel lights pulse)

An aftermarket head unit was installed by previous owner so I pulled the fuse to rule it out as a possible cause and no change.

 

i think (don't quote me on it) the voltage should be stable when RPMs rise. it's been a while.. so i'm not sure LOL. but that would make sense, especially if it's surging at the same time your lighting changes.

 

You're right, that voltage should hold steady no matter the rpm. Just did the same test on my truck and it held to with in +/- .04v. I think I'm convinced...

Thanks for the help

 

I'll also suggest finding a remanufactured alternator instead of the dealer. Dealer will charge you your firstborn child and reman's work just as well.

 

Just a quick update... Replaced the alternator with a re-man from auto zone and it did end up being the problem. Voltage is steady and no more pulsing instrument lights

 

Voltage should not go into the 16s. That's too high.

I saw a battery explode on a car once - a defective alternator was charging a battery at 18V.