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Discussion Starter #1
My wife has a Zap retrofitted 2003 smart ForTwo.
The passenger side headlight was out. Replaced it, still no light.
So I started troubleshooting.
I was an electrician in the Navy for 8 yrs so I have pretty good electrical knowledge albeit on a ship not with 12v DC.
Here is what I did. Cut the wires to the socket. Measured voltage between the two wires. Got about 11.34 volts. Measured from the positive wire to actual ground on the car, got around 11.33 volts.
Bought a new socket and installed it, no luck.
Spliced into the good light and ran jumpers to the bad light. Blew the 7.5 amp fuse. Put in a 10 Amp fuse and both lights came on.
Disconnected everything and put back in the 7.5 amp fuse.
Went back over to the bad side and hooked the positive wire to the socket and ran a jumper from the light socket straight to the ground of the body, no light.
I checked continuity between the ground wire of the bad side and frame of car. It is actually lower in resistance than the good side.
There is no reason in the world that the light shouldn't be on, but it isn't.
Anything you can think of?
 

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Try this. Take the driver's side light bulb (good and in working order) and put it in the pass's socket. (or take the new bulb you bought for the pass side and put it in the driver's side, see if it's working as it should).

One question: Are there separate bulbs for low and high beams on your '07?
 

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Try this. Take the driver's side light bulb (good and in working order) and put it in the pass's socket. (or take the new bulb you bought for the pass side and put it in the driver's side, see if it's working as it should).

One question: Are there separate bulbs for low and high beams on your '07?
It's a 2003 450, yep it should have separate bulbs. :)

He did say that he connected both bulbs to the same circuit and they both worked.

For some odd reason, the right side just isn't lighting despite voltage being present and the bulb working.

Perhaps the problem is at the actual switch for the lights?
 

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Not trying to hijack the thread but I hope my experience could help the OP somewhat. I don't know the 450s at all...

My Dodge caravan lights were behaving strangely years ago (winter 2007). With low beam on, the right would be on, and the left would be off. However, with the high beam on, the left would be on, and the right would be off. I thought both bulbs were bad, so I changed them with new ones. Nope, no change. So I took the van to the dealer. They wanted me to buy a new module for almost $300.00. I asked the tech how he knew it was bad. He said he took one off a new caravan and stuck it in mine, and both lights worked again. I asked him to show me where the module was. It was on the front side of the fusebox, under the hood. So I had them order a new one and to return the next day when the part was supposed to arrive; I would be billed then.

Then, I took out the van from the dealer but checked the lights first. They both worked! So I went back in there and told the Parts guy that my lights fixed and I didn't need the part anymore. He called the tech about it. The tech said it might work for a few weeks but it was failing. But I said, hey, I don't fix anything that is NOT broken. So, I got the order canceled, but got a bill for $80.00 for 'diagnostic' service.

Anyway, I went ahead and read about the problem on the caravan forums. Talk was that the pins on the module might have come loose, so I took out the module, twisted the pins (maybe sixteen all in all) at an angle and pushed back the module into the socket. The lights behaved until today :)

Maybe a bad/loose module for the lights on the 450?
 

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The first problem is that you only have 11.34 volts. If that is battery voltage at the battery with no other loads on then the battery is bad. That is not why the bad light will not illuminate.

The second problem is your light circuit for that non-functional light likely has a bad connection. If you check for voltage with a typical DVOM, or digital volt-ohm meter, then you did not load the circuit because the meter has a input impedance of probably 10 megohms. If the circuit has open circuit voltage but will not carry the load of a good bulb that is a symptom of a bad connection in the circuit.
 

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Discussion Starter #8
That low voltage was from the car sitting a few days.
Drove it to a mechanic and it showed a bit over 12 volts on both sides.
He could not get it figured out. There is just no room to work on this damn car.
So he tied it into one of the parking lights. No biggie, the headlight on the passenger side will now come on when the parking lights are on but my wife drives with headlights on 24/7 for visibility so it will look fine.
I did have what appeared to be good grounds on both sides.
I did find out they are both on their own fuse.
That is strange.
 

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I'm banking on either a bad connection or bad switch to the other bulb.
 

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The first problem is that you only have 11.34 volts. If that is battery voltage at the battery with no other loads on then the battery is bad. That is not why the bad light will not illuminate.

The second problem is your light circuit for that non-functional light likely has a bad connection. If you check for voltage with a typical DVOM, or digital volt-ohm meter, then you did not load the circuit because the meter has a input impedance of probably 10 megohms. If the circuit has open circuit voltage but will not carry the load of a good bulb that is a symptom of a bad connection in the circuit.
Was a CECS major for 3 yrs of college. Voltmeters are very high impedance. (I agree with Rustedwrench.) I think the one thing you didn't do was test for a bad positive wire. Jump the bad side wires one by one to the good side and you might find which one, if not both, that way.
 

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If the car has a SAM, there could be a failed light relay inside the unit. The SAM is the box the under dash fuses are in. It's good practise to mount external low beam relays (and fuel pump relay) on cars with the SAM, to avoid internal damage following arcing at the connectors. Take the SAM down, and check every external connector for corroded/arc damaged pins.

Club smart Car has a thread or two about this.
 

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That low voltage was from the car sitting a few days.
Drove it to a mechanic and it showed a bit over 12 volts on both sides.
He could not get it figured out. There is just no room to work on this damn car.
So he tied it into one of the parking lights. No biggie, the headlight on the passenger side will now come on when the parking lights are on but my wife drives with headlights on 24/7 for visibility so it will look fine.
I did have what appeared to be good grounds on both sides.
I did find out they are both on their own fuse.
That is strange.
The mechanic could not figure it out so he tied it to the parking light. Beautiful. The world is full of hack-it-up so-called mechanics who can not figure things out. Why people continue to patronize them is a mystery to me. You have a simple problem. Well, two simple problems if you count the mechanic working on it.

Let me give you an example. If you take the battery cable to your starter and cut all but one strand of wire in the cable, what do you think will happen? You will still have battery voltage at the starter when you check it with a voltmeter but it certainly will not crank the engine. Your headlight circuit has the same problem. It will not carry the load of the headlight. It has to do with the ability of the circuit to carry current, not just voltage. No electrical work gets done without current flow.
 

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The mechanic could not figure it out so he tied it to the parking light. Beautiful. The world is full of hack-it-up so-called mechanics who can not figure things out.
Ditto, I'd rather have the broken headlight rather than the hack-job parking light powered headlight. :eek:
 

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Discussion Starter #14
No, you don't want a broken headlight, you will get pulled over every night. That is one of the ways cops find people with warrants and driving while drunk. I wouldn't have any problems with that, but I don't want to be stopped every time I drive at night.
He could have found the problem but the labor on these things is insane. Gotta remove the front panel and hope to find it. I told him I didn't want to spend $250 on labor.
I'm happy.
 
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