Wired up new brake/turn signal lamps - only 50% working currently

[bullstanky]

Gents,

I could use a little help with some simple circuits.....I pulled all 8 of the accessory lamps off of my SIII for painting (2 red brake lights, 4 yellow turn signals and the 2 white lamps, whatever they are for...) and have wired up new lamps.

I referenced a wiring diagram in a haynes manual, and while all of it's wire colors didn't match what I saw exactly, I'm pretty sure I got the wiring right (green to green and black to black for the 4 yellow lamps and 2 white lamps, green to green, black to black and red to red for the brake lights).

When I tested the lamps, the 2 brake lights lit up but didn't get brighter when I hit the brakes...probably going to test the switch to see what is up there.

The turn signal lamps only worked on the left side, but both the front and back on the left side worked, and they worked properly.

When I push the turn signal switch to the right, the flasher resistor clicks quickly, like it would if there was a missing bulb, and neither the front or rear lamp comes on, or the turn signal indicator lamp on the dash. I replaced the turn signal switch and the flasher resistor a little while back, but since the original lamps have been off the truck. I replaced it because I was getting an arc when driving the rover with the lamps off that caused the resistor to smoke and burn out....I'm guessing I need to trace the wires from where they exit the resistor to where they meet the lamps...unless there is something easy I am missing...

And then there are the white lamps on the front wings above the turn signals, that as I think about them, don't seem to serve any real purpose...they don't come on at all....and all of the fuses are fine...

I've got a multimeter and can trace every last connection on each of the bad circuits, but figured I'd access the collective intelligence and see if there are any simple solutions before I set out on a wiring safari.

[thixon]

Put on the old bush helmet and load your blunderbuss....let the safari begin.

I hate to say it, but the only thing I can tell you without being there is that you need to check each connection/wire with your multimeter. Get a partner to help push pedals and flip switches for you. If you're sure you got everything right, then double check all your connections first, but based on your post, I'd say you botched something somewhere. Don't feel bad, we've all done it. Good luck.

[jac04]

Don't forget to check all your grounds!

[SafeAirOne]

If all you did is remove and reinstall the light assemblies, then like Travis says, it's most likely bad contacts on the bullet connectors and the 2/3/4-way junction plugs. Those junction plugs are notorious for corroding and making lousy contact. I'd try working the bullet connectors in and out of the junction connectors and check your results as you go. The bulbs often make lousy contact to the terminals inside the sockets and to the ground 'finger' inside the bulb socket in the case of plastic assemblies.

[bullstanky]

If all you did is remove and reinstall the light assemblies, then like Travis says, it's most likely bad contacts on the bullet connectors and the 2/3/4-way junction plugs. Those junction plugs are notorious for corroding and making lousy contact. I'd try working the bullet connectors in and out of the junction connectors and check your results as you go. The bulbs often make lousy contact to the terminals inside the sockets and to the ground 'finger' inside the bulb socket in the case of plastic assemblies.

I replaced all of those old connectors with new crimp on heat shrink butt connectors, so I feel good about the connections and about having wired it up correctly--maybe it's just bulbs making a bad connection--if one bulb is out on a right or left hand blinker circuit, will this kill the entire circuit, or will one of the bulbs still illuminate?

[SafeAirOne]

if one bulb is out on a right or left hand blinker circuit, will this kill the entire circuit, or will one of the bulbs still illuminate?

Up till last week, I would have said that the other bulb will work still, but sometimes it doesn't.

[JimCT]

Use a test lamp and not a multimeter. The multimeter can show the proper voltage but with no amperage drawn the lights wont work. I have done that and drove myself nuts. The test lamps puts a load on the circuit and duplicates what you are trying to fix





Up till last week, I would have said that the other bulb will work still, but sometimes it doesn't.

[thixon]

Use a test lamp and not a multimeter. The multimeter can show the proper voltage but with no amperage drawn the lights wont work. I have done that and drove myself nuts. The test lamps puts a load on the circuit and duplicates what you are trying to fix

With all due respect Jim....Huh?

[JimCT]

A multimeter can show 12V in a circuit, but that is because the meter draws virtually nothing. Still not enough amps to light a bulb. Drives you nuts you read 12V but no lights. A test lamp puts and amperage load on the circuit.



With all due respect Jim....Huh?

[thixon]

A multimeter can show 12V in a circuit, but that is because the meter draws virtually nothing. Still not enough amps to light a bulb. Drives you nuts you read 12V but no lights. A test lamp puts and amperage load on the circuit.

Again, I'm not being a smarty pants, I'm just confused by your post....

I can check for voltage, amperage or electrical resisantance in a circuit with my multimeter (and I thought most others). What's different about how a multimeter registers amperage as opposed to a test light lamp lighting up?

[JimCT]

the voltmeter will not draw enough amperage to show a bad ground. If it is an open circuit of course it shows that , but with corroded LR wiring it may pass 12V's at miniamps, but will not at the amperage an actual light draws. So you will read 12V on your multimeter, but the lamp will still not light.





Again, I'm not being a smarty pants, I'm just confused by your post....

I can check for voltage, amperage or electrical resisantance in a circuit with my multimeter (and I thought most others). What's different about how a multimeter registers amperage as opposed to a test light lamp lighting up?

[thixon]

Okay Jim, now I gotcha,

I wasn't factoring in a crappy connection impeding the flow of electrons through the circuit. Sorry, sometimes I'm thick skulled.

[JimCT]

I think I was not making myself clear. Crappy connections are all over old LR's so been flummoxed by millimeters before!




Okay Jim, now I gotcha,

I wasn't factoring in a crappy connection impeding the flow of electrons through the circuit. Sorry, sometimes I'm thick skulled.

[bullstanky]

Ok gentlemen, I've done some diagnostics and here's what I've found:

When I push the blinker lever to the left, both front and back left blinker lights light up and function properly. When the headlights (and tail lights) are on, and I push the lever to the right, both front and back right blinker lights light up, but blink very slowly, and when the headlights (and tail lights) are off, neither front nor back right blinkers light up, and the clicker clicks very quickly like when a bulb is out.

When I hit the brakes, the tail lights don't get any brighter, but the back left blinker lights up.

It looks like two of my positive leads are mixed up.... Any idea which ones?

[greenmeanie]

Given your symptoms I and presumably an original wiring harness I predict its bad earth connections. Your head lights and side lights are on the hot feed from the ignition switch while the indicators and brake lights are on the switched section. The side lights should have no common connection point with the indicators with the one exception being the ground point. As you have one side flashers working properly I would assume that the power feed to the indicator switch is working.

If you have a bad earth on one circuit it can try and back feed another circuit to find a path to ground. For a while Fords were notorious for flashing the brake or tail light at the same time as the indicators due to a poor design in this respect. I'd go and find the respective grounds for the brakes and RH indicator (it was on a common connector behind the light cover at the back of the truck on my IIA. Disconnect all the earths and make the connection for each in turn while operating the circuit.

Just guessing of course over the internet.

[SafeAirOne]

The side lights should have no common connection point with the indicators with the one exception being the ground point.

Unless this is the worst-case-scenario, that is. You know, the one where there was a short and a wire burned up in the bundle, making all sorts of non-factory circuits.

This problem is easy to figure out if you know how to use a multi-meter, but 'multi-meter' and 'how electricity works' is something for somebody else to teach. I'll bet there are plenty of sites and YouTube videos on this subject.

[greenmeanie]

Unless this is the worst-case-scenario, that is. You know, the one where there was a short and a wire burned up in the bundle, making all sorts of non-factory circuits.

.
Ah yes. I've been there too but we don't want to scare the poor man just yet. Maybe tomorrow.....

[SafeAirOne]

Ah yes. I've been there too but we don't want to scare the poor man just yet. Maybe tomorrow.....

Well, it HAS been a month since this problem was first presented. I think it's time.