1977 fj 45 electrical help needed

[texex92]

I installed a new radio and have been having issues with speakers cutting out when engine is above idle speed. I checked the the voltage on the battery and all is good at 12.5 with engine off I then started engine and tested voltage which came in at 17.4. As suspected the voltage increased above normal. It appears that radio shuts off output at higher voltage. I believe the output from alternator is too high causing radio to stop normal output. The head unit never shuts off it just shuts down sound. Has anyone experienced this? Is there a way to adjust voltage regulator? Is regulator bad? Do I have another issue I have not thought about? Is it the alternator. Any help is greatly appreciated

 

[crumbo]

replace regulator

 

[texex92]

I replaced the voltage regulator and still am getting high volatge readings. I suspect it is a ground issue. Can anyone point me in the right direction for steps to test wires in system? My guess is the regulator is experiencing a drain and thinks it needs to increae output. ANy help is greatly appreciated.

 

[DSRTRDR]

consult the wiring diagram for your year cruiser

 

[bj40green]

Check the VR for good ground. The VR is grounded per the housing but also via the white/black wire to the Alternator.
This white/black wire is for eliminating ground differences between frame/firewall and engine.
If the VR has a bad or missing ground the output Voltage starts to "float" sending the wrong (higher) Voltage to the (F tab) on the Alternator.
Check how much Volts you have on both sides of the "F" wire between VR and Alt. Should be the same and less than 15 Volts. Typical is between 13.8 and 14.8 Volts when charging, less (6 to 7V) when battery is full.

Rudi

 

[78fj40mg]

First check the voltage regulator, secondly check the power connection and GROUND, if it's not a good ground it could burn the radio.

 

[texex92]

Currently there is a ground wire from the battery to the engine. Should there be a wire going to frame as well?

 

[bj40green]

Yes, there should be a wire (cable) from the frame to the inside fender.

Rudi

 

[texex92]

when you say from the frame to inside fender. Can you clarify. Should there be one from the baterry "-" to frame or inside fender or from the insider fender to the frame. Any suggestion on where to look on inside fender as I dont see one.

I was just able to take some readings on the various wires they are as follows

B wire at alternator 17 with regulator connected 12.8 without regulator connected
F wire at alternator regulator connected varies from 15.9 sometimes to 1o smetimes very weird even if the F wires drops to 10 the B wire stays aournd 16-17. I would expect this to drop as the abttery appears fully charged.

I dont see to se a fusible link on the B wire that goes to the ammeter and back to the "+" of the battery the po may have rerouted wires not sure.

Sorry for the all the questions this is very confusing as what the beast is doing.

As a side note my ammeter is always showing a discharge. Could there be a problem with the wire from the B terminal on the altrnator to the ammeter back to the battery? Shoule I replace the wires from the alternator to the ammeter back to the battery? I should probaly insert the fisible link while replace the wire. Not sure if the PO replaced and hid it somewhere i can see it.

 

[texex92]

Further reserach shows that the B wire from the alternatr goes directly to the battery Through a two battery selctor switch which think i am going to remove as I only have one battery. It just complicates things. I alos noticed that the E wire from the back of the alternaotr is grounded to the inside fender i am assuning this is correct. I cant tell where the e wire from the regualtor is attached but i tested it and it it also grounded somewhere.

 

[bj40green]

when you say from the frame to inside fender. Can you clarify. Should there be one from the baterry "-" to frame or inside fender or from the insider fender to the frame. Any suggestion on where to look on inside fender as I dont see one.

I'm not familiar with FJ's but I know that there should be a wire/cable/strap between the frame and the inside fender.
Hopefully somebody will put a pic in.
Or you can run a cable from the -bat to the fender or firewall.

I was just able to take some readings on the various wires they are as follows

B wire at alternator 17 with regulator connected 12.8 without regulator connected
F wire at alternator regulator connected varies from 15.9 sometimes to 1o smetimes very weird even if the F wires drops to 10 the B wire stays aournd 16-17. I would expect this to drop as the abttery appears fully charged.

So you're saying that the Voltage on the B lug alternator is always higher than the Voltage on the F terminal from the VR?

I dont see to se a fusible link on the B wire that goes to the ammeter and back to the "+" of the battery the po may have rerouted wires not sure.

Depending on the year there is or was not a fusible link close to your battery. It's not important at this moment.

As a side note my ammeter is always showing a discharge. Could there be a problem with the wire from the B terminal on the altrnator to the ammeter back to the battery? Shoule I replace the wires from the alternator to the ammeter back to the battery? I should probaly insert the fisible link while replace the wire. Not sure if the PO replaced and hid it somewhere i can see it.

Reading this and your next posting the ammeter is out of the loop and will not show charging, only discharging.


Rudi

 

[bj40green]

Further reserach shows that the B wire from the alternatr goes directly to the battery Through a two battery selctor switch which think i am going to remove as I only have one battery. It just complicates things. I alos noticed that the E wire from the back of the alternaotr is grounded to the inside fender i am assuning this is correct. I cant tell where the e wire from the regualtor is attached but i tested it and it it also grounded somewhere.

I want you to do a test to check out if there is any resistance in the ground circuit.
Start engine and hook up the voltmeter, one lead to the Alternator housing and the other lead to the Voltage Regulator base (bare metal) housing. When all is perfect the result should be 0.0 Volts.
Keep the meter atached and let a buddy rev up the rpm's and switch on the headlights to create a current draw. Take another reading.
Report back what you did, what you noticed while doing the tests and the readings from the tests.


Rudi

 

[texex92]

Yes it appears the readings show that the output at the b lug is higher than voltage on the f wire.

 

[bj40green]

Yes it appears the readings show that the output at the b lug is higher than voltage on the f wire.

Typical case of a "bad or missing ground".
Can be the wiring but also the alternator itself.
Maybe one of the other electrical guru's can chime in here?

Rudi

 

[texex92]

Baed on your instructions the results are as follows:

Black to alternator frame red to regulator chasis

Idle +35 mv

Idle lights on 75mv

Engine at 2000 rpm 350 mv
Engine at 2000 rpm with lights on 225 mv

 

[bj40green]

As you can see there is a potential differential between the engine block and the frame/firewall.
In the original set-up there is the white/black stripe wire between the Alternator and the Voltage Regulator.
That's the wire you say is connected to the fender and the other end you can't trace but measures 0 ohm.
Ad a new wire between the Alt. and the VR. to eliminate this problem. I don't guarantee that this solves the problem but it's one step closer in the elimination process.

Good luck,

Rudi

 

[texex92]

Replaced theta wire and went direct from e on alternator to e on regulator same issue is occurring

 

[bj40green]

Next shot....
Same test as before but now the Volt meter hooked up between:
1. The - battery post and the Alt. housing. Idle, rev up, lights, no lights.
2. Between - battery post and VR housing. Idle, rev up, lights, no lights.

Good luck,

Rudi