Pulsing lights

[ram_man]

Hey guys my honda civic does this weird thing when your driving the lights pulse. It's very fast. And non stop. The dash lights don't seem to do it but the headlights and done lights do.
The battery and alternator have tested good. The car has an aftermarket alpine stereo but that is it. No amps or anything like that.

At idle is fine as soon as soon as you touch the throttle it starts doing it. The ground wire on the front of the engine looks good and tight battery terminals are good and clean. So what should I check?

Any idea how to narrow this down? Thanks.

 

[Gotch]

Sounds like the alternator even if it tested "good".

Could be the voltage regulator or a diode on its way out. The only sure way to test is to scope the alternator...or pull the diode trio and test each one.

 

[HerrStig]

The alternator itself needs to be well grounded. Sometimes the mount itself isn't that good a connection.

 

[meep]

is it a rhythmic flash or more random?

I've seen this in a lot of chrysler vehicles and haven't completely figured it out in the past.

you can try metering for voltage loss (engine running, all accessories on) on every ground path you can find, including alt frame to battery (-) post, and alt (+) to batt (+) post, looking for inadequate conductivity.

I had one vehicle that measured over 1 volt of loss on the ground path when /everything/ was on. Installing new grounds took away the loss but the flicker remained. (the transmission shifted better however). THAT vehicle later received a new batt, and the problem went away.

diodes are suspect but their symptoms are usually worse at idle than at cruise.

 

[ram_man]

It's rhythmic . I wasn't sure If the alternator belt could do it. I just replaced it and got it tight but the belt wore in and now when I burp the throttle it's make a very quick split second eek sound not loud or anything but just a hair. I figured I would snug it up but to me that wouldn't make sense as being the issue.

 

[Sequoiasoon]

On my Sonata (and others) one of the first TSB's is for electrical and lights pulsing etc. One of the techs on another site said that for them it's almost standard practice to fix all the grounds before any further diagnosis. Most new cars are much better at paint/corrosion protection. Unfortunately (foryunately?) it's also done before everything is bolted together. What you wind up with is trying to make a good ground with ONLY what threads contact through paint.

Clean all the grounds! Follow wire from battery ground to where it bolts to body. Remove the screw, grind paint off where it contacts flat surfaces and inside threads if possible. Coat the area with Kopr Shield http://www.tessco.com/products/displayProductInfo.do?sku=437469 or some other version (copper anti-sieze) or dielectric grease.

Do the same for large body to motor on both ends. Maybe even at alternator and positive wiring. Hyundai is of course different but they had TSB's for new alternator to battery wiring with corrosion issues.

 

[The_Jeff]

Also ground the computer and body control module as good as you can! They control the alt in these newer cars. Civics in particular are funky as they cut power to 13.5 volts under cruise to save gas.

For a wacky test connect pins 4 and 5 on the OBDII connector. They're PCM ground and chassis ground. They SHOULD be the same, if this fixes things you have a floating ground somewhere. You can do this by plugging in (virtually) any scan tool if you're squeamish.

 

[NHGUY]

On Chrysler vehicles (especially 4G minivans) it could be:

Low battery
Bad alternator
Dirty connection between BCM and Fuse Distribution block.
Dirty cable connection at battery
Bad ground
Worn/dirty headlight switch contacts.

As for a Honda,maybe some of the same problems could apply?

 

[Tegger]

Originally Posted By: ram_man
Hey guys my honda civic does this weird thing when your driving the lights pulse. It's very fast. And non stop. The dash lights don't seem to do it but the headlights and done lights do

What year Civic?

Is the Check Engine light on? (it may not be)

What you describe sounds a lot like the Electrical Load Detector (ELD) having gone bad. This is a notorious problem with some years of Civic.

 

[ram_man]

05 civic

 

[ram_man]

I just did some reading and apparently the Canadian built civics don't have a eld. Mine was built in Canada. It's just in the fuse box right? I guess it would easy enough to check....

 

[Tegger]

Originally Posted By: ram_man
I just did some reading and apparently the Canadian built civics don't have a eld. Mine was built in Canada.

It doesn't matter where the vehicle was actually assembled. Cars conform to the regulations and conditions for the market into which they are sold, not the one in which they are assembled. If your Civic was intended for sale in the US, then it has an ELD.

Originally Posted By: ram_man
It's just in the fuse box right? I guess it would easy enough to check....

Your year has a plug-in ELD. Lucky you. I see that there is a TSB out (05-006) covering all '05 Civics for faulty ELDs. The TSB says that a P1298 DTC will be stored in the ECM. Proper troubleshooting is required to confirm the ELD as the culprit. Visit your dealer.

Flat-rate time listed by American Honda for this repair is 0.4 hour. But that was just what Honda would pay the dealer for the in-warranty repair. Your dealer will probably charge you for more time than that for your out-of-warranty repair, but if you know the TSB's time, you may be able to bargain down.

 

[ram_man]

Is it just that brown square thing in the fuse box? I don't have honda dealer close and wouldn't mind just doing it myself

 

[Tegger]

Originally Posted By: ram_man
Is it just that brown square thing in the fuse box? I don't have honda dealer close and wouldn't mind just doing it myself

The ELD is underneath the fuse box; you can't see it right now. You need to completely remove the fuse box from the car in order to be able to change the ELD.

If you want to take a crack at it yourself (without having done any actual diagnostics!!!), I can send you the TSB. Just PM me with an email address.

 

[meep]

...never heard of that part. besides what the name implies, which voltage bus rides on it? everything besides the starter? only certain circuits?

 

[ram_man]

How do you actually diagnose the part

 

[R2d2]

Some 8th gen 4cylinder Accords had a similar issue. The solution was a bigger battery (v6) version.

 

[ram_man]

Honda does seem to use little batteries..... Wonder why?

 

[Tegger]

Originally Posted By: ram_man
How do you actually diagnose the part

To test it, you're looking for certain voltages between two terminals on a particular connector. I don't have the shop manual or the EWDs for your specific car, so I can't tell you which terminals do what. And I don't have the experience to be able to figure it out on a general basis.

Under conditions of high load, the ELD should allow charging voltage to rise to its usual 14VDC (plus or minus) and stay there. High-load would include something like the rear window defogger, the A/C, or the headlights. But with all three loads on at the same time to ensure maximum draw, a VOM should show a steady ~14VDC charging voltage at the battery terminals.

I've asked before (without answer) and I'll ask again:
1) Is your Check Engine light on?
2) Have you checked for stored codes whether the light is on or off?

 

[Tegger]

Originally Posted By: meep
...never heard of that part. besides what the name implies, which voltage bus rides on it? everything besides the starter? only certain circuits?

Only the voltage regulator. The ELD sends a signal to the ECM informing the ECM as to what the electrical load is at any particular time. The ECM then makes the decision whether or not to cause the voltage regulator to allow full charging-voltage.

Besides its communication lines to the ECM and VR, The ELD has only an inductive connection to the rest of the electrical system, much like a hand-held Fluke voltage tester.

The ELD is meant to increase a vehicle's gas mileage by reducing the drag load that the alternator normally applies. It is only installed on US-market cars, because the US is the only country in the world with gas-mileage regulatory targets that automakers must meet.

Further reading of my documentation seems to suggest that a blown fuse can cause problems that might be blamed on the ELD. It would behoove the OP to check each and every fuse in both fuse boxes.