Electrical Gremlins...

[Liam]

My 1978 40 is having some electrical issues. It seems like when i have more than three things on the electrical draw is too great and ends up shutting the radio off.

First off, if i have the lights on the left blinker does not work at all. The right one does but the left one is nada. The flashers still work with the lights on though. Also, if i have the lights and heater on and then turn anything else on the radio shuts off and then when i shut something off it will come back on.

I have a new alternator and red top battery and have also upgraded my wiring from the firewall forward.....everything worked fine, but now has gone to s***.

any ideas?????

 

[Liam]

what? no ideas????

 

[John Smith]

My 1978 40 is having some electrical issues. It seems like when i have more than three things on the electrical draw is too great and ends up shutting the radio off.

First off, if i have the lights on the left blinker does not work at all. The right one does but the left one is nada. The flashers still work with the lights on though. Also, if i have the lights and heater on and then turn anything else on the radio shuts off and then when i shut something off it will come back on.

I have a new alternator and red top battery and have also upgraded my wiring from the firewall forward.....everything worked fine, but now has gone to s***.

any ideas?????

In my experience it is usually the grounds or lack thereof that cause those issues, especially with the lights. Check all your grounds at the tail lights and blinkers in front, you will probably find your problem there. If your radio is not wired directly to the battery with a fuse remove it from whatever circuit it is on now and wire it to the battery. Do NOT use fuse taps or splice anything into the factory harness. If you need to add a bunch of accessories install a new fuse block off of the battery.

 

[Liam]

In my experience it is usually the grounds or lack thereof that cause those issues, especially with the lights. Check all your grounds at the tail lights and blinkers in front, you will probably find your problem there. If your radio is not wired directly to the battery with a fuse remove it from whatever circuit it is on now and wire it to the battery. Do NOT use fuse taps or splice anything into the factory harness. If you need to add a bunch of accessories install a new fuse block off of the battery.

i've got a new fuse block off the battery. I will check my grounds, maybe that's the problem...

 

[71-CRUISER]

Check your emergency flasher switch (internaly). All of the circuts for the turn signals and the flashers run through that switch and iff some of the interior contacts become corroded you will have issues with your signals and flashers.

 

[Pin_Head]

The left blinker and radio issue are probably unrelated unless the radio always flips out when you turn the blinker on. The radio issue is probably a bad connection causing a voltage drop somewhere in the circuit after the point from where the radio circuit brances off from the fuse block where all the other circuits start. The blinker issue is usually a bad ground, but it isn't clear from your description whether the problem is that it fails to light up or it fails to flash.

 

[igotta40]

I have similar issues but only at idle. If I bump up the idle a hundred rpm or so everything goes to working. I'm thinking voltage regulator contacts or increased impedance in the wiring and/or connectors due to age.

Hope that helps.

 

[Liam]

The left blinker and radio issue are probably unrelated unless the radio always flips out when you turn the blinker on. The radio issue is probably a bad connection causing a voltage drop somewhere in the circuit after the point from where the radio circuit brances off from the fuse block where all the other circuits start. The blinker issue is usually a bad ground, but it isn't clear from your description whether the problem is that it fails to light up or it fails to flash.

the blinker issue was a bad ground for sure...all fixed. But if i have my radio and lights on and then flip the blinker the radio cuts out and then will come back on when i turn the blinker off or it will come back on then shut back off in tune with the blinker.

I just replaced the VR to see if that helps, but havent run it long enough to see if it is charging the battery. There is definitely too much current pull coming from somewhere. The radio is connected directly to the battery, so when it cuts out i am assuming there is not enough charge to keep it alive...

 

[Pin_Head]

If the radio amp is over 100 watts, then the total power demand may exceed the maximum alternator output, tripping a low voltage protection mode in the amp. The only solution for this would be a more powerful alternator.

 

[Liam]

If the radio amp is over 100 watts, then the total power demand may exceed the maximum alternator output, tripping a low voltage protection mode in the amp. The only solution for this would be a more powerful alternator.

i do have an Amp that is pushing power to the radio as well. I think you are right about not enough power. If i get a more powerful amp will i need to replace my VR?

 

[Pin_Head]

i do have an Amp that is pushing power to the radio as well. I think you are right about not enough power. If i get a more powerful amp will i need to replace my VR?

Do you mean alternator? Most more powerful alternators come with a built in regulator, but it you get an externally regulated alternator (like a large case Ford) your new/old VR will probably work fine.

 

[Liam]

Do you mean alternator? Most more powerful alternators come with a built in regulator, but it you get an externally regulated alternator (like a large case Ford) your new/old VR will probably work fine.

no i am talking about an Amplifier which is in my glove box. The PO put it in there along with some kick ass speakers. I just changed my alt to a 55amp alt....

 

[Pin_Head]

A 55 amp alternator should be able to keep up with the 30 amp chassis load (lights, motor, accessories) plus a 200 watt amplifier. If the load exceeds the max alternator output, the voltage will drop to the battery voltage and trigger the amp low voltage protection.

 

[Liam]

A 55 amp alternator should be able to keep up with the 30 amp chassis load (lights, motor, accessories) plus a 200 watt amplifier. If the load exceeds the max alternator output, the voltage will drop to the battery voltage and trigger the amp low voltage protection.

so WTF then. Why am i having all these issues?? Maybe i dont have my Alt hooked up right.....

i hate electrical s***.....you've definitely been a help though

 

[Pin_Head]

Figure out if you are having voltage drop issues first. What is the voltage at the battery, alternator B+ lug and at the amplifier when the engine is running at 1000 RPM with all the lights and stuff on? It should be approximately the same at all those points and between 13.5 and 14 V.