Dimming Headlites

[Mr. Man]

Probably been discussed but we all know about 'search'.

Coming home tonite from my local cruise nite I was driving with the hi-beams on (such that they are) and I goosed the gas to clear the cob-webs out of the car and I noted as the car down shifted the headlights dimmed noticeably. Tried it a couple of times with the same result, same for low-beams too. It takes a few seconds for the lites to charge back up to full brightness. Is this normal? Never noticed it on the 04 MM. If it's not normal where should I start looking.

Thanks in advance :)

[jwibbity]

alternator?!?
how long have you had the battery?!?!

were you going WOT?? I think I've read that the alternator shuts off at WOT

[EMAS]

Yes having the lights dim at WOT and the voltage on the gauge drop is normal and shows that your charging system is operating as intended. The alternator's output voltage is controlled by the PCM and when the PCM senses WOT it shuts of the alternator to provide maximum HP to the wheels.

[Mr. Man]

Battery is new early last year although it did go dead over the Winter. It's 1000/850 cca battery.

I was not going WOT. Just enough gas to drop it a gear from say 45mph.

Car only has 22K so I would think the alternator is good unless they poop out over time regardless of use. IDK

[jwibbity]

Battery is new early last year although it did go dead over the Winter. It's 1000/850 cca battery.

I was not going WOT. Just enough gas to drop it a gear from say 45mph.

Car only has 22K so I would think the alternator is good unless they poop out over time regardless of use. IDK

go to a shop and have them check your charging system. It'll let you know if you have a dying alternator or a weak battery

[Bigdogjim]

AAA if your a member will come to your house and check it for free! :up:

Most auto parts stores will also check it for you.

Good luck with it.

PS: I never noticed my lights dimming on my '03. FWIT

[CWright]

That happened to me before swapping to HID's. The charging system was working fine but the battery was weaker than it should be. I put a charge on the battery overnight and did not have a problem anymore.

[Ken]

That happened to me before swapping to HID's. The charging system was working fine but the battery was weaker than it should be. I put a charge on the battery overnight and did not have a problem anymore.With only 22k, I'm guessing the car isn't driven often. Maybe battery is just not at full charge. Maybe a trickle charger is needed.

[Mr. Man]

Going to NH in the car next week so hoping the charge in the battery will get full.

How long does it take an alternator to recharge a battery from say I had to jump start the car this morning?(stock alt)

[fastblackmerc]

Going to NH in the car next week so hoping the charge in the battery will get full.

How long does it take an alternator to recharge a battery from say I had to jump start the car this morning?(stock alt)

Depends on how fast you go, what accessories you used, etc.

[Mr. Man]

Depends on how fast you go, what accessories you used, etc.
Would a 350 mile trip do the trick?

[EMAS]

Yes a 350 mile trip should top up the battery. The amount of current a battery can accept varies depending on how charged it is. The closer it is to being fully charged the slower it charges. So it could take the same time to raise if from a 90% state of charge to full as it did for it to reach that 90% state of charge from 50%.

[NavySeabee]

Would a 350 mile trip do the trick?

I'll bring my cables, just in case. :)

[RF Overlord]

...and I'll bring my jump-box. ;)

[fastblackmerc]

Would a 350 mile trip do the trick?

Yes it would do the trick...

[Ms. Denmark]

I'll bring my cables, just in case. :)

I have cables. Car has been starting OK as long as it doesn't sit for a long time. :)

Mr Man

[justbob]

All my lights dim and dance to the cams at the lights. I call it character. :)

Now go tickle your battery Eric! :D


Self proclaimed Builder Of Badassery.

Buy it, Break it, Build it BETTER.
"Since 2004"

[Mr. Man]

All my lights dim and dance to the cams at the lights. I call it character. :)

Now go tickle your battery Eric! :D


Self proclaimed Builder Of Badassery.

Buy it, Break it, Build it BETTER.
"Since 2004"
That made me laugh..............:cuke: occupied! :D

[1Marauder]

My lights dim at WOT as well, which is every time I am behind the wheel!!!!!

[JBeezy]

I've never been WOT. Smh!!

[Vostok]

Mine has done this since purchase. I just assumed it was the PCM thing with the alternator going neutral at WOT.

[Guittard22]

I'll bring my cables, just in case. :)

Phone a friend if need be I got a battery Charger in the Chrysler Marauder lol still trying to get up for dinner Thursday night but I would need to Switch a shift .

[Mr. Man]

Got a new battery as the 20 month old one gave up the ghost. Alternator is doing its thing fine.

Can someone in laymans terms briefly explain the process of unhooking what where to find out if there is a mystery drain. I know it involves unhooking one of the battery terminals and a test light and pulling fuses but I'm not sure of the exact process.

Thanks.

[Spectragod]

Got a new battery as the 20 month old one gave up the ghost. Alternator is doing its thing fine.

Can someone in laymans terms briefly explain the process of unhooking what where to find out if there is a mystery drain. I know it involves unhooking one of the battery terminals and a test light and pulling fuses but I'm not sure of the exact process.

Thanks.

You'll need a DVOM or clamp on DC meter to do it right, the car should not draw more than 80-100ma at rest.

A test light will not give you accurate results as there is always I draw. Can it be done with a test light..... yep, you can drive round on temporary spares for weeks on weeks too, but I wouldn't do it. You can get cheap DVOM's, and it will give you the best results.

[Bluerauder]

Got a new battery as the 20 month old one gave up the ghost. Alternator is doing its thing fine.

Can someone in laymans terms briefly explain the process of unhooking what where to find out if there is a mystery drain. I know it involves unhooking one of the battery terminals and a test light and pulling fuses but I'm not sure of the exact process.

Thanks.

Eric,

Before you go running off looking for a complicated electrical issue, I would check the most obvious stuff first. In this case (based on your symptoms from the past week or two), I would check the battery connections first. Make sure that the terminals are tight and that the posts are clean to allow a good contact with the terminals. FLAPS or AutoZone sell a wire brush tool specifically intended to clean battery posts and terminals. Terminals should be tight when the bolts are tightened. If not, use some battery post lead shims.

Did you install your new battery or did the service department ?? Did they clean any debris out of the battery tray and unclog the drain hole so the battery is not sitting in a pool of water?

Make sure there is good contact on the ground wire. If the battery drain symptoms persist, then look to other sources of power drain.

[DWSTANG67]

Got a new battery as the 20 month old one gave up the ghost. Alternator is doing its thing fine.

Can someone in laymans terms briefly explain the process of unhooking what where to find out if there is a mystery drain. I know it involves unhooking one of the battery terminals and a test light and pulling fuses but I'm not sure of the exact process.

Thanks.

You can unhook either the positive terminal or the negative terminal, it is safer to disconnect the negative. this is done when using a amp meter or the amp function on a multimeter. Amp meters will measure the amp draw from the battery, but must be hooked in series, thats between the battery terminal and the cable you removed never ever cross positive to negative with a amp meter you will damage the meter or blow the internal fuse,( thats why it safer to disconnect negative due to if you used the positive terminal than touched any ground you would damage your meter) if you see more than 50 to 100ma your have a drain

[Mr. Man]

____________

[DWSTANG67]

I not sure what time i getting home on Sunday from Maryland

[Mr. Man]

I not sure what time i getting home on Sunday from Maryland

Forgot about that. I'll see what I can come up with in the meantime.

Party hearty though :party:

[fastblackmerc]

Sounds like a grounding issue. Check all the engine compartment grounds. They all have black wires and green colored bolts.

[fastblackmerc]

I have cables. Car has been starting OK as long as it doesn't sit for a long time. :)

Mr Man

I'd invest in a battery tender. Since my MM isn't a DD I hard wired a battery tender and keep it connected when not in use.

[Mr. Man]

So I got a friend and a multimeter and we watched a couple of Youtube videos to see how to test the power draw on the battery at rest. We unhooked the negative terminal and hooked the red test lead of the multimeter to the negative battery connector and the black test lead to the negative battery post. Put the multimeter on DC AMPS and it registered .13 amps. According to what we understand that is normal for modern car. We pulled every fuse one at a time and the reading never changed. We did not pull any of the relays or if I remember correctly something called IC's which only seem to be in the fuse block in the engine compartment.


The battery at rest, engine off read 12.4 volts which I think is normal. The old battery only read about 9 volts. Alternator was a steady 14.2 amps so that seems to working.

Did we do the test correctly?

[Mr. Man]

On another note while pulling fuses I noted 4 or 5 fuses for just audio and/or CD. A couple were 5 amp and the others 15 amp. Why so many? The fuse guide didn't really give more info as to what fuse did what audio function. Is there a better resource as to what each fuse specifically does?

[fastblackmerc]

So I got a friend and a multimeter and we watched a couple of Youtube videos to see how to test the power draw on the battery at rest. We unhooked the negative terminal and hooked the red test lead of the multimeter to the negative battery connector and the black test lead to the negative battery post. Put the multimeter on DC AMPS and it registered .13 amps. According to what we understand that is normal for modern car. We pulled every fuse one at a time and the reading never changed. We did not pull any of the relays or if I remember correctly something called IC's which only seem to be in the fuse block in the engine compartment.


The battery at rest, engine off read 12.4 volts which I think is normal. The old battery only read about 9 volts. Alternator was a steady 14.2 amps so that seems to working.

Did we do the test correctly?

Yes, you tested correctly. The draw in normal. 12.4 is normal for the battery as well as 14.2 for the alternator output.

Old battery is shot.

[fastblackmerc]

On another note while pulling fuses I noted 4 or 5 fuses for just audio and/or CD. A couple were 5 amp and the others 15 amp. Why so many? The fuse guide didn't really give more info as to what fuse did what audio function. Is there a better resource as to what each fuse specifically does?

Fuses:

#1 - 15A - Audio, CD changer (self explanatory)

#2 - 5A - Audio (probably protects the amp/sub assembly in the trunk)

#8 - 25A - Radio noise capacitor (stops electrical interference in the audio system)

#13 - 5A - Audio Run & Accessory (protects the radio in Run & Accessory)

There are also 2 circuit breakers / Maxi fuses in the Power Distribution box for the audio circuit protection.