Power supply wiring?

[350runner]

I remember someone saying power goes through the head light switch then fuse box. If this is true please post a diagram. I would like to bypass the switch. Thanks

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[MrMarty51]

Whatcha doing, whatcha mean, bypassing the switch, You going to have headlamps/tail lamps come on soo as the enjun is started, and, drawing current from the starter whilst cranking onher ? ? ?

 

[350runner]

I've noticed I can maintain 13.5 - 14+ volts at the battery, but the dash not so... even when I turn on the AC the Windows slow or just don't... Yea I can wire up the relays for the Windows but that's bypassing the problem. I wasn't to cure the problem. If it means bypassing the switch with five relays, so be it

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[flyboy1100]

I remember someone saying power goes through the head light switch then fuse box. If this is true please post a diagram. I would like to bypass the switch. Thanks

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might only be for the lights, and for sure the dash lights.

 

[chengny]

Ceasar, before you do anything drastic, check a couple of things. The PW system is grounded to the common ground bus block, then through the sheet steel of the cab, across the flat braided ground strap that runs from the RH side of the firewall to the RH cylinder head. Through the engine block, to the alternator bracket and finally across the negative battery cable to the negative post.

Check that the connector at the bus block is tight. Check the bus block itself is in good contact with the cab body (unbolt it, clean the threads and under the shoulder of the bolt, clean the internal threads in the body, make it tight):

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Next weak spot is the cab to engine block strap. Same drill on this - both ends of the strap need to be clean and tight. Any and all cab mounted electrical equipment uses this cable as part of the path to ground. Another path is through the body mount bolts, into the frame, from the frame to the body sheet steel, to those small ground wires on the radiator frame and finally to the battery negative. But imagine the rust on just the body mount bolts and how it can impede the flow of electrons.

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After the engine block, the next weak spot is the alternator bracket (generally where the negative battery cable is connected). There must be a clean/tight connection between the bracket and block and also at the termination of the negative cable:

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It's a long journey for those electrons to make it from the PW motors all the way back to the negative post on the battery. And they have to go through the bus block, braided grounding strap, alternator bracket and the negative cable.

As a test, try running a good 10 gauge jumper wire from the common ground bus block straight over to the battery negative. If your dash shows better voltage and the windows move faster, the problem is not on the hot side but rather with the ground circuit.

 

[MadOgre]

After the engine block, the next weak spot is the alternator bracket (generally where the negative battery cable is connected). There must be a clean/tight connection between the bracket and block and also at the termination of the negative cable:

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It's a long journey for those electrons to make it from the PW motors all the way back to the negative post on the battery. And they have to go through the bus block, braided grounding strap, alternator bracket and the negative cable.

As a test, try running a good 10 gauge jumper wire from the common ground bus block straight over to the battery negative. If your dash shows better voltage and the windows move faster, the problem is not on the hot side but rather with the ground circuit.[/QUOTE]

I was thinking of running a cable from the alternator body to the ground cable that is connected to the alternator bracket. What do you think Jerry? is it worth my time?

 

[chengny]

The alternator itself plays no part in the ground circuit for cab mounted equipment. I think they just chose the alternator bracket to connect the negative cable because it was, securely mounted to the engine block, in handy place near to the battery and out of harm's way (from heat, oil, vibration, chafing, etc).

I think a lot of the problems people have with their PW's operating slowly has to do more with the ground side of the motor than the hot side.

I have recently been involved in a couple of discussions that concerned the ground path for the PW motors. Even before the lengthy, multi connection part of the ground circuit that starts at the common ground bus and ends at the battery negative, there is a convoluted circuit that leads from the PW motor to the common ground bus block. This is cut and pasted from one of those discussions:

The ground circuit on these systems is insane. Yes, it's true that the local switch reverses the polarity in the leads to the motor. The positive side is pretty straight forward; pink (hot) comes in to the switch and when the button is moved up or down the power is supplied to whichever side of the motor is needed.

At the same time that the hot side is switched, the ground leg is also switched. But the ground leg does not terminate locally. One of the two remote power leads from the master switch takes on the duty of the ground leg.

So the negative path to ground is: out of the motor windings, back through the switch, into the harness connector, out of the connector on one of the remote power leads (which one depends on whether the window is being raised or lowered), all the way back to the driver's master switch, through that switch, and finally out on the black ground lead to the common grounding bus block.

See if you can follow this diagram - the red arrows indicate the positive side and the blue is for negative side/ground path:

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[350runner]

Jerry. Trust I know the importance of a good ground. Securing good grounds was one of the first things I did when I got the truck. I have done the big three, gone through replacing all the grounds and adding some more. I'll try taking a wire from the ground buss to the batt to see what it does this afternoon. Thank guys

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[350runner]

So I tried running a wire from the batt negative to the ground distribution in the cab and nothing changed. Then I got out the multi meter and read: batt 14.11v, alt- batt supply 14.12v, power distribution block under the hood 12.56v? All numbers recorded while AC, fan, and headlights were on. Next I put a wire from the alternator- batt supply (fused inline) to the power distribution block... 13.89 volts. Good enough for me now the volt meter on the dash stays above 13.5. It no longer dips below 12v at lights. The fan blows allot faster even at med high speed. I left the alternator sensing wire at the back of the alt- batt connection. Hope this helps someone else.
Edit: I still have a 4 gauge wire from the alt- batt post to the positive batt terminal.
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[350runner]

After thinking I'll give it a week of drive time keeping a record during trips. A week from now I'll move the sensing wire to the distribution block on the firewall and test that out. Feels good seeing the voltage on the dash where it should be.

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[350runner]

First start this morning dash volt meter read 14v all connections under the hood read the same. Headlights on still 14v after a 30 min drive the dash vm read 13.5v. I checked the connections under the hood at my destination all read 14v, dash still 13.5 the Windows up/ down speed are faster. Dash lights are brighter. Windshield wipers are faster and the engine runs a little smoother as I have the ignition coil and choke plugged into the fuse box along with all other accessories.
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[350runner]

Well all its operating extremely well. Windows still function fast dash lights are still brighter. AC fan motor still spins faster than b4. Dash volt meter still reads 14v on start up till approx an hour later, then drops to 13.5 - 13.95 depending on what accessories I'm running. All in all is well worth it. I'd suggest it to anyone b4 buying relays for the Windows and headlights. Just make sure all ground connections under hood and dash are excellent.

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[MadOgre]

So I tried running a wire from the batt negative to the ground distribution in the cab and nothing changed. Then I got out the multi meter and read: batt 14.11v, alt- batt supply 14.12v, power distribution block under the hood 12.56v? All numbers recorded while AC, fan, and headlights were on. Next I put a wire from the alternator- batt supply (fused inline) to the power distribution block... 13.89 volts. Good enough for me now the volt meter on the dash stays above 13.5. It no longer dips below 12v at lights. The fan blows allot faster even at med high speed. I left the alternator sensing wire at the back of the alt- batt connection. Hope this helps someone else.
Edit: I still have a 4 gauge wire from the alt- batt post to the positive batt terminal.
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You have a problem wire between the distribution block and the starter. Seeing as the alternator generates the usable power while engine is running your wire from alt to distribution block has effectively bypassed the problem.

 

[350runner]

Yea that's what I thought, then I replaced all said charging system wires with new 12 gauge wire. Still had that same issue. Issue was voltage drop(too much length) in the wires from the batt to starter to distribution block to fuse box. Way to much. Hints the new voltage readings This is the reason newer vehicles have fuse boxes under the hood next to the batt and alternator little to no voltage drop then

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[350runner]

To test my theory on the voltage drop I went to each connection and read less voltage at every connection

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