Surge in the alternator??

[79D50]

I will start off by saying that everything works on the truck. Lights, HVAC, wipers, dash lights etc. I have checked all of the grounds including the main off the battery into the wiring harness and they are solid with no corrosion. I checked underneath the dash and there are no loose connections of funky wiring. All of the fuses are good and the connections are tight. So, here is the dilemma. As you all know the dash lights in these trucks are dim due to the Hitachi 35 amp and the general design. My stereo and brake lights along with everything else described above worked great. Well, as of late it seems like my alternator is surging power (the best way I can explain it) because now all of a sudden after 4 months or driving the truck my dash lights are way brighter, my HVAC blows harder and subsequently my brake lights no longer work.

 

I have replaced the brake switch and checked the wiring at the alternator, checked the bulbs in the tailights (all operable) and have drawn no conclusions. My turn signals, parking lights and reverse lights all work. Just no brake lights so it is not the bulbs as the brakes share the same bulb as the parking lights. The other day it quit surging (dash lights dim) and the tailights along with everything else worked normally as it should.

 

Why am I losing my brake lights and is my alternator going out. You wouldn't think it would surge before shiting the bed but????? Please help as I can't drive around without brake lights.

 

 

 

Thanks in advance!!

[DISLEXICDIME]

I will start off by saying that everything works on the truck. Lights, HVAC, wipers, dash lights etc. I have checked all of the grounds including the main off the battery into the wiring harness and they are solid with no corrosion. I checked underneath the dash and there are no loose connections of funky wiring. All of the fuses are good and the connections are tight. So, here is the dilemma. As you all know the dash lights in these trucks are dim due to the Hitachi 35 amp and the general design. My stereo and brake lights along with everything else described above worked great. Well, as of late it seems like my alternator is surging power (the best way I can explain it) because now all of a sudden after 4 months or driving the truck my dash lights are way brighter, my HVAC blows harder and subsequently my brake lights no longer work.

 

I have replaced the brake switch and checked the wiring at the alternator, checked the bulbs in the tailights (all operable) and have drawn no conclusions. My turn signals, parking lights and reverse lights all work. Just no brake lights so it is not the bulbs as the brakes share the same bulb as the parking lights. The other day it quit surging (dash lights dim) and the tailights along with everything else worked normally as it should.

 

Why am I losing my brake lights and is my alternator going out. You wouldn't think it would surge before shiting the bed but????? Please help as I can't drive around without brake lights.

 

 

 

Thanks in advance!!

 

i wonder if its the turn signal switch

[79D50]

turn signals and hazards work flawlessly.

 

Could this be my voltage regulator perhaps? Is this located on the driver side fender (there are 2 there)? Truck is a 76 620 with an L18.

[datzenmike]

1/ Get a test light and check both sides of the brake switch. Should have 12 on one side and on both when the brake peddle is down.

 

No power to switch:

Check the 4 way emergency flashers. If they don't work then the 15 amp fuse is blown ... it's on the H terminal on the fuse box.

 

Yes power is there:

Go to next step

 

 

2/ Disconnect the 10 pin connector under the pass side seat and check for power on both the LightGreen/Red and the LightGreen/Black wires going back to the dash when brake is applied.

 

No power:

The the turn signal lever has to disconnect the brake light on the side selected, in order for the turn signal to flash the shared bulb. When the lever returns to off the brake light is connected back up. Something is wrong here.

 

Yes there is power on both:

Go to next step.

 

 

3/ Behind the right rear tail light is a 6 pin connector. Check for power on the LightGreen/Red and Black wires

 

No power:

Wires are broken between here and the plug under the seat

 

Yes there's power: Well by now you probably fixed or found the problem because there is a very slim chance that both brake/signal wires are broken between here and the bulbs....

[79D50]

Thanks Mike. I will check all the following and report my findings.

 

I forgot about the switch under the seat.

[79D50]

1/ Get a test light and check both sides of the brake switch. Should have 12 on one side and on both when the brake peddle is down.

 

Checked and operating correctly. 12 on one side and 12 on both when brake peddle is down.

 

No power to switch:

Check the 4 way emergency flashers. If they don't work then the 15 amp fuse is blown ... it's on the H terminal on the fuse box.

 

Fuse is good and power is good. Hazards work fine.

 

Yes power is there:

Go to next step

 

 

2/ Disconnect the 10 pin connector under the pass side seat and check for power on both the LightGreen/Red and the LightGreen/Black wires going back to the dash when brake is applied.

 

Yes, power is good on both of these wires when brake peddle is pressed and brake switch is open. Also checked the 10 pin connector at the firewall behind the package tray and power is good here as well.

 

No power:

The the turn signal lever has to disconnect the brake light on the side selected, in order for the turn signal to flash the shared bulb. When the lever returns to off the brake light is connected back up. Something is wrong here.

 

Turn signals and flashers work well with the brake peddle depressed and released.

 

Yes there is power on both:

Go to next step.

 

 

3/ Behind the right rear tail light is a 6 pin connector. Check for power on the LightGreen/Red and Black wires

 

Both wires have power on this connector.

 

No power:

Wires are broken between here and the plug under the seat

 

The wires are fine as everything in the back works as it should except the brakes. The bulbs for each brake light assembly (4) are fine and the bulbs for the brakes work as well for the parking lights just not the brakes. Filaments are good.

 

Yes there's power: Well by now you probably fixed or found the problem because there is a very slim chance that both brake/signal wires are broken between here and the bulbs....

 

Double checked everything...I am still screwed. :blink:

[datzenmike]

So you have brake power all the way to the bulbs????

[79D50]

I did evertything you recommended and the results suggest that I do have brake power to the bulbs. I don't know what else to try.

 

I checked the horn fuse as I was reading in other threads and that was fine as well.

[79D50]

Forgot to add that my electric choke quit working and my horn never has worked. Possible relay issue? I don't even know where the horn relay is...

[datsunaholic]

Are you 100% completely sure you have power to the brake light bulbs? It is physically impossible for you to have power to the hazard bulbs (making the rear lights blink) yet NOT have the lights work with the brake pedal, IF you have power to the sockets. It's the same circuit from the hazard switch back.

 

Just because the running lights work doesn't mean the bulbs are good. Just because you have power to the running lights doesn't mean you have power to the brake lights. Different circuit.

 

IF the lights blink (brightly) with the hazard switch on, do a sanity check and try it with the running lights and hazards on. If the rear bulbs go OUT instead of going bright/dim with the hazards, that's a sign that you don't have a good ground, and the bulbs would be grounding through the other filaments.

 

 

But, as stated before: If the rear turn signals and hazards are working properly (the lights light up brightly) yet you don't have brake lights, the ONLY possibilities are

 

1) No power to the brake light switch

2) Bad turn signal switch (and the signals can still work if the switch is bad- it has a "center" position that connects both sides to the brake light switch)

3) Possibly the hazard switch, as it's hooked in parallel (easy way to prove this: turn on the hazard switch and press the brake pedal. The lights quit blinking and all the corner lights illuminate)

 

 

Note: These only apply to systems that use combined brake/turn signals in back. Split systems won't have the combined wiring through the turn signals and hazards for the brake lights.

[79D50]

Are you 100% completely sure you have power to the brake light bulbs? It is physically impossible for you to have power to the hazard bulbs (making the rear lights blink) yet NOT have the lights work with the brake pedal, IF you have power to the sockets. It's the same circuit from the hazard switch back.

 

Thanks for the info man! I am 110% positive I have power to the brake light bulbs. The brake bulbs work with the hazards, turn signals and running lights. The filamets light up and are good.

 

Just because the running lights work doesn't mean the bulbs are good. Just because you have power to the running lights doesn't mean you have power to the brake lights. Different circuit.

 

understood

 

IF the lights blink (brightly) with the hazard switch on, do a sanity check and try it with the running lights and hazards on. If the rear bulbs go OUT instead of going bright/dim with the hazards, that's a sign that you don't have a good ground, and the bulbs would be grounding through the other filaments.

 

Hazards blink brightly and when the running lights are on they still work but just go a bit dim. I checked and rechecked the ground to where I am going insane.

 

But, as stated before: If the rear turn signals and hazards are working properly (the lights light up brightly) yet you don't have brake lights, the ONLY possibilities are - This is my situation.

 

1) No power to the brake light switch - I checked this with a voltmeter. Power to one side when static and power to both sides when depressed to create the circuit. I need to verify this for sanitys sake with a jumper this afternoon. A jumper should make the brake lights come on with or without the switch correct?

 

2) Bad turn signal switch (and the signals can still work if the switch is bad- it has a "center" position that connects both sides to the brake light switch)- I will be taking this apart and cleaning it with a light sand and dielectic grease. This could be the culprit.

 

 

3) Possibly the hazard switch, as it's hooked in parallel (easy way to prove this: turn on the hazard switch and press the brake pedal. The lights quit blinking and all the corner lights illuminate)- Yes, I tried this and it only works when the brake lights illuminate. Since this problem has begun, pressing the brakes with the hazards on does nothing. It may be the hazard switch. Need to clean this up as well.

 

 

Note: These only apply to systems that use combined brake/turn signals in back. Split systems won't have the combined wiring through the turn signals and hazards for the brake lights. - I have the combined system. If I unplug the 6 pin round connector to the right rear tailight the other side goes dark.

[79D50]

I am at a total loss. I tested the alternator, battery, relays, switches etc. I cleaned all the contacts and grounds in the turn signal switch. I tried 3 different hazard signals and all woked the same. I cleaned the fuse box and added all new fuses.

 

I found out though that I am getting power to the connector under the passenger seat for hazards and turn signals but no power is coming through for the brakes. The test light would only light up for hazards and signals. But Datsunholic stated that it doesnt matter. They are on the same circuit. If I have power to the hazards then I should have brake lights. I checked all the wiring and grounds under the dash and followed the harness and found nothing.

 

Could it still be a bad turn signal switch?

 

Anyone have a spare turn signal switch in good condition they want to sell me? I have free beer and pizza for any locals who really know electric to come eyball this thing to see if I missed anything.

[79D50]

BUMP....

[datzenmike]

You said:

 

I did evertything you recommended and the results suggest that I do have brake power to the bulbs. I don't know what else to try.

 

 

 

Now you say:

 

I found out though that I am getting power to the connector under the passenger seat for hazards and turn signals but no power is coming through for the brakes.

 

You have 4 way emergency flashers and turn signals but no brake power at the plug under the pass seat.

 

So, go back to the brake switch and test for power. As I said in my first post.

 

1/ Get a test light and check both sides of the brake switch. Should have 12 on one side and on both when the brake peddle is down.

 

No power to switch:

Check the 4 way emergency flashers. If they don't work then the 15 amp fuse is blown ... it's on the H terminal on the fuse box.

 

Yes power is there:

Go to next step

 

 

2/ Disconnect the 10 pin connector under the pass side seat and check for power on both the LightGreen/Red and the LightGreen/Black wires going back to the dash when brake is applied.

 

No power:

The the turn signal lever has to disconnect the brake light on the side selected, in order for the turn signal to flash the shared bulb. When the lever returns to off the brake light is connected back up. Something is wrong here.

 

Yes there is power on both:

Go to next step.

 

 

3/ Behind the right rear tail light is a 6 pin connector. Check for power on the LightGreen/Red and Black wires

 

No power:

Wires are broken between here and the plug under the seat

 

Yes there's power: Well by now you probably fixed or found the problem because there is a very slim chance that both brake/signal wires are broken between here and the bulbs....

[79D50]

The brake switch is fine. Tested it with a light. One side is hot and when then button is released, both sides are hot. The plug under the seat only lights up with the teste with the flashers and the turn signals. With just the brakes depressed, there is no power to that plug....I even jumpered the switch thinking the brake switch was no good...Same result...I'm about ready to light this truck on fire or drive it off a cliff - kidding!!

 

I think this is my problem...

 

2/ Disconnect the 10 pin connector under the pass side seat and check for power on both the LightGreen/Red and the LightGreen/Black wires going back to the dash when brake is applied.

 

No power: I do not have power to this connector with JUST the brakes depressed.

The the turn signal lever has to disconnect the brake light on the side selected, in order for the turn signal to flash the shared bulb. When the lever returns to off the brake light is connected back up. Something is wrong here. The turn signals and hazards work great...I checked the switch for corrosion (none) and sanded all the contact points. Perhaps this switch is just bunk although it feeds power to the brake switch at the peddle...Maybe between the peddle and the connector under the seat has a bad connetion although I've checked and rechecked all wiring...still no power..

 

Sorry if your slapping your forehead but I am the first to admit I am not good at auto electrical. I can build anything mechanical but electric is not my fortay.

[datsunaholic]

You have that backwards... the brake pedal switch feeds power to the turn signal switch, not vice-versa.

 

So... Do the brake lights work when you turn the turn signal one way or the other? That would indicate a problem with the switch if they DO work (or at least one side) when the switch isn't centered.

 

If they STILL don't work, then maybe the wire that comes from the brake switch isn't making it all the way to the turn signal switch. Obviously the wires from the turn signal switch to the back work, since the signals work. So there is only 2 possibilities- the switch is bad, or the wiring to it is bad.

[79D50]

You have that backwards... the brake pedal switch feeds power to the turn signal switch, not vice-versa.

 

There is definitely power at the brake peddle switch. Tested this 6 ways to Sunday.

 

So... Do the brake lights work when you turn the turn signal one way or the other? No, they do not work. That would indicate a problem with the switch if they DO work (or at least one side) when the switch isn't centered.

 

If they STILL don't work, then maybe the wire that comes from the brake switch isn't making it all the way to the turn signal switch. The power is getting there as the signals work great. Obviously the wires from the turn signal switch to the back work, since the signals work. So there is only 2 possibilities- the switch is bad, or the wiring to it is bad. I'm sold on a bad turn signl switch as everything else pans out.

 

Let me ask you this. If the brake switch power is good and is feeding to the turn signal switch to allow that to operate, could the turn signal switch still be bad? With the lever centered the power turns the corner back through the switch and to the rear correct? I checked this contact point at the switch and it looked ok.

 

Getting my hands on a turn signal switch is good operating condition has shown to be tougher than it seems. Ebay has one but the plug looks different than mine.

[datsunaholic]

The brake pedal switch only feeds power to the brake lights. It is on the always-hot fuse.

 

The turn signals are fed power from the IGN circuit, THROUGH the blinker can.

 

However... the turn signal SWITCH distributes power from both. So it's fed power from both circuits separately.

 

There are 2 sources, 4 outputs, and 3 switch positions.

 

It works like this:

 

 

When the turn signal switch is CENTERED, the power from the brake light switch is fed directly to both the L and R rear turn signals. The front turn signals are disconnected. Power from the blinker can is not connected to anything in this position.

 

When the switch is in the LEFT position, power from the brake light switch is fed only to the right-rear turn signal. Power from the turn signal blinker can is sent to the left front and left rear circuits. The right-front remains disconnected.

 

When the switch is in the RIGHT position, power from the brake light switch is fed only to the left-rear turn signal. Power from the turn signal blinker can is sent to the right front and right rear circuits. The left-front remains disconnected.

 

 

We've already ascertained that the input for the turn signals (out of the blinker can) is good. We've also determined that the output from the turn signal switch is good. That's proven because the turn signals work.

 

You've stated that there's power to both sides of the brake switch when the pedal is pressed. That means that the problem HAS to be either between the brake pedal switch and the turn signal switch, or in the switch itself. Because the brake lights don't work with the turn signal switch in any position, that generally, but not absolutely, means that the switch isn't getting power from the brake light switch. Either a wire has corroded in one of the connectors, or is broken at a connector or at the switch itself.

 

You need to trace the brake light switch output to the turn signal switch input. It's ONE wire. If, with the pedal depressed and the ignition off, you still have power all the way up into where the wires are soldered to the switch contacts, then it's the switch itself. But I'd bet that somewhere the wire is broken or corroded long before that.

[79D50]

That makes a lot of sense. This is a good electrical education for me even though this will be my third night digging into the truck....I will trace the one wire. This time I will take pictures of what I do. On the switch itself (I tested this last night) there were only 2 wires that were getting power off the test light out of the 4 soldered on the board. They were for the signals (L&R). I will grab some pics tonight of progress. I think we are getting closer. :D

[79D50]

I tore apart my entire wiring harness between the brake switch and the turn signal switch. There are no breaks in the wires and all of the connectors (spades, round male/female, and square block connectors) are all in good shape. There was no corrosion or otherwise. I tested everything with the tester light. All of the electrical aside from the brakes works flawlessly. It HAS to be that turn signal switch. I swapped hazard switches with the same results. The brake lights (before they died permanently) did work intermittently which would suggest a broken or loose connection in the switch.

 

DATDOUG says he has one and I am picking it up this weekend to test. If it is not the turn signal switch then I think I am going to have a bonfire with the truck as the guest of honor....lol... :P

[79D50]

The Gods have answered my prayers. I go out to fire up the truck this morning to warm it up and as I am backing out of the garage - low and behold - the damn brake lights work. The turn signal work, the hazards work and now the brake lights come on strong. It has to be the turn signal switch. I was fiddling with it again last night testing leads etc. This will be confirmed over the weekend at DATDOUG's

 

I have to say thanks to all those who helped troubleshoot. It was a great education and I learned more about the truck so that is a good thing. My next step after this fix is to yank off the entire dash assembly and clean up the connectors, re-route the wires, and add grounds where grounds are needed. I have a brand new dash to stick in the truck anyways. Plus, I can add some body seam caulk to the backside of the firewall as they may be a small leak there.

 

Any other things I should look for while the dash is out?

[79D50]

I finally got my new TS Switch yesterday. The brake lights working (as stated in the post above) was short lived. All my running lights, hazards, TS and brake lights work great thanks to the new switch.

 

I also found the other problem. The title mentions surge in alternator. I noticed that the electrics were working better i.e. lights were brighter and WW were faster etc. This ended up being a faulty VR which ultimately killed my alternator and drained my battery. I almost had to get towed Saturday afternoon. I replaced the alternator with a 1978 200 SX IR and jumped the VR plug as directed by Hainz. The alt works great but the install leaves very little adjustment room becuase the casing is bigger than OEM and hits the idler arm. I tried a 78 200 SX belt and the stock belt and neither one worked. One was too large and the other too small. I ended up using my slightly stretched belt that was already on there and it works great. I will end up taking a measurement of the belt and try to find a part number to replace it with.

 

After the new battery was installed it fired up and ran perfectly with a full 15 volts charging the battery. Everything works great. I now have 50 amps at my disposal which is more than enough.

 

Finally the electric problem is solved. :D