Engine dies when headlights are turned on

[bavarian06]

Art,

Do you know how to use a multimeter? If so take voltage readings at your battery

1. when the car is off

2. after the car has been started

3. at 2000 RPMs

Also check your alternator and belt. Is the alternator turning? Does the belt have enough tension?

In the early Zs like yours, the headlight switch completes the ground path for the circuit, so it isn't a short. Search around this site. Dave, aka Zs-ondabrain, posted a link for the 71 FSM supplement. That has the wiring diagrams in it.

By the way, it is helpful for you to put the year of your car in your posts.

Good luck and let us know what you find out.

i actually have a multimeter, not sure exactly how to use it. i know i rotate the dial to DC and set on a level of sensitivity correct?

i recently replaced my battery.

[bavarian06]

for the most part, i'm almost 90% sure its the bad connection where the fuse box pigtails wires connects to the strand of wires that lead up the dash and out through the firewall.

why i know is that i would wiggle that connection point and my headlights would finally turn on, and sure enough i'm able to start the car.

EE was definitely not my major in college (finance major here); can someone explain to me why would the parking lights work (along with the dash lights, dome lights) but once the i rotate the stalk once more to turn on the headlights everything goes dead/dark.

Edited January 31, 2011 by bavarian06

[bavarian06]

hm... that piece its a voltage regulator? i think that may be it as well.

"A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level"

[SteveJ]

i actually have a multimeter, not sure exactly how to use it. i know i rotate the dial to DC and set on a level of sensitivity correct?

i recently replaced my battery.

That's pretty much it. Just select a range that is greater than 12 volts.

Also look at these links for more information. The second set of links is for measuring resistance in a circuit. Knowing how to use a voltmeter and ohmmeter can get you a long way toward figuring out what it wrong with your car.

As far as replacing connectors, I can't say enough good things about Vintage Connections. Del sells most of the connectors you need, as well as nice ratcheting crimpers and an extracting tool to remove terminals from the connectors.

Now for the ammeter, if you start the car and take the tach up to 2000 to 2500 RPM, does the ammeter move? I would expect it to go toward the positive side.

[kenz240z]

Hi Art, the part pictured in the bottom photo on post #11 is the accessory relay. It provides power to the rear hatch defroster, maybe something else. Refer to a wiring diagram and it should show any other circuits controlled by the relay.

[bavarian06]

Hi Art, the part pictured in the bottom photo on post #11 is the accessory relay. It provides power to the rear hatch defroster, maybe something else. Refer to a wiring diagram and it should show any other circuits controlled by the relay.

Hi Ken,

Can anyone else confirm this? I was about to buy and replace this item:

http://www.thezstore.com/page/TZS/PROD/12-4081

[SteveJ]

Art,

That is a voltage regulator, and it will work on your car. Conventional wisdom suggests replacing both the alternator and regulator at the same time since failure of one can damage the other. In the past, I have been lucky in bucking conventional wisdom on this. YMMV.

By the way, if price is a consideration, you might also try Rockauto for the alternator and regulator. Another course of action is to find an automotive electrical shop and having them rebuild your alternator.

[bavarian06]

As far as replacing connectors, I can't say enough good things about Vintage Connections. Del sells most of the connectors you need, as well as nice ratcheting crimpers and an extracting tool to remove terminals from the connectors.

Now for the ammeter, if you start the car and take the tach up to 2000 to 2500 RPM, does the ammeter move? I would expect it to go toward the positive side.

thanks for the link! the website has exactly what i'm looking for. i'll read up on the how-to and test the voltage levels and report back.

[bavarian06]

Art,

That is a voltage regulator, and it will work on your car. Conventional wisdom suggests replacing both the alternator and regulator at the same time since failure of one can damage the other. In the past, I have been lucky in bucking conventional wisdom on this. YMMV.

By the way, if price is a consideration, you might also try Rockauto for the alternator and regulator. Another course of action is to find an automotive electrical shop and having them rebuild your alternator.

I see. In this very same HELP ME! section, a member replaced his alternator and his car would die out while he was driving. He ultimately fixed the problem by replacing the new alternator with the old one again. :paranoid:

Basically I dont want to replace components in fear of developing additional problems. Plus once too many things are swapped out, its harder to diagnose the source of the problem since there are now too many variables.

[kenz240z]

Hi Art, as I mentioned, the part in the photo from post #11 is the accessory relay. The voltage regulator is located in the engine bay and is mounted on the right inner fender.

[Zed Head]

Basically I dont want to replace components in fear of developing additional problems. Plus once too many things are swapped out, its harder to diagnose the source of the problem since there are now too many variables.

This is a good thought.

You should test your voltage regulator and alternator with the lights off and engine running. That will tell you if they are okay. If your regulator and alternator are putting out the correct voltage with the lights off, you should leave them alone. It's actually a good easy way to get used to using a multimeter. Connect the positive lead to the positive post on the battery and the negative to negative, set the scale to read around 12 volts, start the car with the lights off, and take some readings at idle and at higher rpm. Hold the engine at higher rpm until the voltage reading stabilizes. You will probably be at around 13 at idle and 14 - 15 at higher rpm. If they test out okay, leave them alone, and focus on the headlight switch issue.

From what I've read, your problem has something to do with bad wiring or maybe a loss of ground when you use the headlight switch. Your "beating on the dash" story is significant, that would have nothing to do with your regulator or alternator since they are in the engine bay.

The picture of the white wire doesn't look very good, it looks like it got pinched and shorted through the insulation some time in the past.

[bavarian06]

This is a good thought.

You should test your voltage regulator and alternator with the lights off and engine running. That will tell you if they are okay. If your regulator and alternator are putting out the correct voltage with the lights off, you should leave them alone. It's actually a good easy way to get used to using a multimeter. Connect the positive lead to the positive post on the battery and the negative to negative, set the scale to read around 12 volts, start the car with the lights off, and take some readings at idle and at higher rpm. Hold the engine at higher rpm until the voltage reading stabilizes. You will probably be at around 13 at idle and 14 - 15 at higher rpm. If they test out okay, leave them alone, and focus on the headlight switch issue.

From what I've read, your problem has something to do with bad wiring or maybe a loss of ground when you use the headlight switch. Your "beating on the dash" story is significant, that would have nothing to do with your regulator or alternator since they are in the engine bay.

The picture of the white wire doesn't look very good, it looks like it got pinched and shorted through the insulation some time in the past.

ok, i'll definitely will test the voltage once i get the chance.

can you possibly answer this qt?

"can someone explain to me why would the parking lights work (along with the dash lights, dome lights) but once the i rotate the stalk once more to turn on the headlights everything goes dead/dark."

it was almost comical when i banged on the dash and the headlights turn on; hence being able to start the engine. as mentioned in previous post, i think its the male/female terminal connectors needs to be replace leading out of the fuse box. cause when i banged on the dash, it probably shook that strand of wires, getting a better connection?