(Dim?) Wit's End

[jblueridge]

After days of labor and many purchases of parts, my BJ74 is still electrically dead. Turn the (newly replaced) key and I get nothing. Turning the new starter switch directly with a screwdriver gets me nothing also. Horn and lights do not work.

Stuff done so far
Removed all connections to my 12V converter.
Deleted 12V stereo.
New starter switch
New battery cables
New starter relay
Three new fusible links, the ones right by the rear battery.
Batteries charged by a high-tech new-age charger that can detect faults. No faults found.
I cleaned and sanded the ground wire connections I could find.
The main ground to engine block. Body ground to battery. Starter flange bolt to frame.
I added 2 new grounds from body to frame and from block to frame (right side).
I pulled the starter. It works just fine, but I had it checked by a pro. Starter is a-ok.
All fuses check out as okay.
Voltmeter shows power is getting to starter terminal.

I am not sure what else I can do.

Any advice would be helpful.
Thanks

 

[coldtaco]

does the starter turn when you take said screwdriver across the big lug and a ground?

 

[cruiserdan]

Did it quit out of the blue or was it after working on something?

 

[jblueridge]

It died out of the blue weeks ago.
The only strange thing that may or may not be related is I plugged an RC plane charger into the (converted to 12V) cig lighter and it made the 12V radio come on.
I drove to town and back after that. About two hours later I had no juice.

does the starter turn when you take said screwdriver across the big lug and a ground?

I have not tried that as the starter works when bench tested and the horns & lights are dead too. There is about 24V of power making it to the positive terminal on the starter right from the battery.... I guess that is the solenoid connection.

 

[cruiserdan]

Does the dome light work?

Does anything activate when you turn the ignition switch (IE the volt meter or the indicator lights such as filter and parking brake)?

 

[jblueridge]

When I turn the starter switch, nothing lights up at all. Nada.
Dome light does not work at all.
Two weeks ago when I was concentrating on only the horn and lghts, their relays would buzz, but the lights and horn did not work at all. That made me think of dying batteries and bad grounds.
I don't know where the grounding points are for horns and lights.

Before the thunderstorm began here just now, pulled the horn relay and found 24.5 volts on one of the relay connectin points. I might make a jumper to sort of bypass that relay.

I still feel there is a major grounding point I need to find. The manuals I have are not helpful.

 

[cruiserdan]

There should be two grounds from the negative terminal. One to the engine block and one to the left inner fender. If both are present and well connected you most likely have a positive feed problem in the fuse link or the legs from it to the truck harness.

 

[jblueridge]

I sanded the ground connection point on the block, near the left motor mount.
I did the same to the connection on the left fender.

Power is getting through the new fusible links.
After the fusibles, those three wires, black, red and white, go into the wiring loom. Not sure how I would be able to check for faults in the loom.
The power wire for the horn carries the juice the the horn relay. That relay is held n a plastic bracket.
Where does the horn switch connect to ground?

 

[doug720]

If a 70 is similar to a 60, there is a large plastic plug behind the dash cluster that contains grounds and a couple of odd color wires. I've seen posts where this connection has melted and caused loss of power - ground.

Maybe worth a look. I remember you other posts, so maybe this was already discussed?

 

[cruiserdan]

The horn circuit grounds at the steering wheel.

 

[cruiserdan]

You should have battery power at the stop and dome fuses in the block by the accelerator pedal.

 

[cruiserdan]

According to the wiring diagram the gauges are grounded at point "c" which is indicated to be "located under left front pillar".
Power to the stop and dome should be coming through the white fuselink leg.

 

[ozcrusier]

So if everthing is dead in the truck your not getting power to the ignition. Have you checked reset the circuit breakers in the fuse block. I would also pull the bulkhead conector apart and check for burnt connectors in there.

 

[cruiserdan]

20 amp "power" and 30 amp "heater".

 

[jblueridge]

Thanks for so many replies!

If a 70 is similar to a 60, there is a large plastic plug behind the dash cluster that contains grounds and a couple of odd color wires. I've seen posts where this connection has melted and caused loss of power - ground.
/QUOTE]
"Dash cluster" means the unit that holds speedo, tach etc? I have never gotten back behind that. I can try.

You should have battery power at the stop and dome fuses in the block by the accelerator pedal.

I detached the fuse block and looked behind. I expected to find a "bus" like I have on my BlueSea 12v box. Nope. I think I checked power going in. I'll check again.

Have you checked reset the circuit breakers in the fuse block.

20 amp "power" and 30 amp "heater".

I thought the 20 amp Power breaker was for the "power tap" under the hood on the right side; I will check them but I don't think all the power runs through them.

The horn circuit grounds at the steering wheel.

So when I honk the horn the ground for the solenoid part of the relay is at the steering wheel. The power for the lights themselves also grounds there?

According to the wiring diagram the gauges are grounded at point "c" which is indicated to be "located under left front pillar".

I saw that in the wiring diagram too. I don't know exactly where to look "under the pillar".

I'll go probe the fuse box.

 

[ozcrusier]

According to my manual the circuit breakers are in the fuse box right hand kick panel

 

[jblueridge]

According to my manual the circuit breakers are in the fuse box right hand kick panel

Yes, they are in the fuse box. I put the end of a paperclip into the Reset hole. There was no click or anything: I think those had not been "tripped".

I would also pull the bulkhead conector apart and check for burnt connectors in there.

The bulkhead connector is the large one bolted up to the dash above the steering column?

I used the multimeter to check for current draw. I placed the meter in between the battry positive and the ring terminal that connects all the fusible links. At most it was 2 milliamps. Maybe that's the clock pulling power.

I pulled the top row of fuses which seems to be those circuits not switched though the key/ignition switch.
24.9 volts on one side of the fuse for the Cig lighter, dome light and brake light circuits.
Nothing at all in the headlight circuits. I turned the headlight switch on and there was still no voltage at those two circuits (left and right headlights).

With the headlight switch On, I happened to check the first 3 circuits again. The voltage for Cig lighter, dome light and stop lights drops way down when the headlight switch is on. Down to 2 volts or less.
I have no idea what that means.

Not sure what I should do now.
If I have the "ignition" key turned to the Run position, the other "switched circuits should show power at their fuse box connections, right?

 

[cruiserdan]

A voltage drop like that indicates a poor connection, not limited to a ground. That was easily said. Finding it is the challenge.

Circuits like lighter should energize when the key is in accessory or run.

A note in the fuses. You do not actually need to pull them to check for voltage. If you look at the back face of the fuse (where the amperage is stated) you will see a couple small holes on either side of the number that allow you to probe them to check them in place.

 

[cruiserdan]

Do you have a repair manual with wiring diagrams? That document identifies the ground locations, albeit a bit vaguely.

 

[jblueridge]

I have the FSM tht I downloaded from MUD.
The grounding points are stated at the bottoms of the pages, but I a still not sure where to look.
"Under the front pillar" is not very specific.

None of the wiring diagrams seem to perfectly match my BJ74 with 13BT. Here are some excerpts.

My starter switch has 3 positions, not like this pic from the manual.

This pic from the same source has what seems to be the right starter switch but it shows EDIC stuff that I don't have.