More electrical gremlins (1 Viewer)

[badsamaritan]

I've been chasing electrical issues with my 12/73 FJ40 since I bought it. Symptoms are:

• blows 20A heater fuse and lose my gauge lights and my fuel, oil, water temp gauges, but only while driving. I can't tell if it's at higher RPM or? But everything works great while Key On, Engine Off in my driveway or while idling.
• Harness is a refurb from @Coolerman, new Alt, New VR.

Things I have noticed recently that may be clues

• Blinkers blink fast, and charging indicator moves to the left in rythmn with the blinkers. Flasher is the new relay style.
• Alternator has a 3 blade connector in the rear. VR is also a 3 terminal connector. Harness only has 2 wires that go into the alternator
• Brown discoloration marks are on the blue/white wire coming off of the alternator

 

[badsamaritan]

Looking at my wiring diagram it looks like the Alt only uses the F and E terminals, so my harness is correct

 

[badsamaritan]

I found a loose connection on the ammeter which I tightened up, I also googled the PN for my alternator and realized that I got a 50A version from Rock Auto and not the stock 40-45Amp version. The ammeter no longer bounces wildly with the blinker on, but I haven't run the vehicle yet to see if it's still blowing the 20A fuse

Would using a 50A alternator on stock wiring and gauges be causing my issues? I'm guessing since the ammeter is 30A that it would.

 

[Engineer8000]

The ammeter only measures current from the alternator to the battery. I don't think having a 50A alternator will make a difference since charging current is typically very low. I guess if your alternator or regulator failed you may pass more current out of the battery but that also would have nothing to do with your 50A alternator.

 

[SteveH]

If your battery were 100% dead, and the alternator was putting out the full 50 amps, then you might have a scenario where wires could be seeing excess current, but I doubt in the real world that you will have a problem.

You 'alt' gauge should ping to the left in cadence with the turn signals due to the inrush of current to the light bulbs. This is normal for vehicles with alternator gauges.

Fast-blinking turn signals might indicate a bulb problem (or dreaded LED bulbs). Check your bulbs, sockets, and (especially) grounds for the hazard/turn signal system.

 

[badsamaritan]

The pinging to the left was pretty extreme, like 0 to -30, then back to 0. Fixing the loose connection at the ammeter really improved that. Now it just barely flickers to the left. The blinking is still faster than I think it should be so I will keep checking around. All of the light houses are brand new and all working so maybe a bulb isn't seated all the way or the flasher ground isn't that great.

 

[Cromagnon]

Fast-blinking turn signals might indicate a bulb problem (or dreaded LED bulbs). Check your bulbs, sockets, and (especially) grounds for the hazard/turn signal system.

The DOT standard for flash rate is 60 to 120 flashes per minute. Not sure what the "dreaded LED bulbs" are about. You mention you have the "new relay flasher." Can you be more specific? If you have incandescent lamps in all of your housings you need to make sure they are the correct size (wattage) and that the housings have good grounds. If you do a search in the forum you will see that this horse has had its skin flailed off of it from the continuous beatings. If you have the relay that @Coolerman provides it won't matter what type of bulbs you have, but you will need good grounds for the signals to work.

 

[badsamaritan]

Instead of the Toyota OEM flasher I have this relay:

Relay Turn Signal Flasher - OEM - FJ40, FJ45, FJ55 - 7/1970-1984

OEM Toyota - Fits FJ40/45/55 7/1970 - 10/1984 This is an updated Toyota part. It replaces the big, plastic flasher box located underneath the dash. Functions the same, but in a smaller package. - The included nut and bolt are used to ground the black wire to the chassis. - Plugs into the factory...

cruisercorps.com

I'm going to check grounds again this weekend but all of the housings and bulbs are all brand new, and they all work. The only bulb not present is my license plate light which I don't think comes into play.

What started all of this was my heater fuse blowing but only when the rig was moving under load. It wouldn't blow sitting in the garage or at idle regardless of what was turned on or off.

I'll also get a video of the flashing, maybe it's normal, I don't really have anything to compare it to

 

[badsamaritan]

Added a ground to the VR and re-did the ground for the flasher. VR now charges like it should and flashing is now at a normal rate. I let the truck idle in my driveway for 15min no issues.

Went for a 10min drive around my block at varying speeds and the fuse blew as I was pulling up the driveway. No ****ing clue what is up with this thing.

 

[Cromagnon]

Try this. Disconnect the heater and the heater switch from the harness. Replace the fuse and drive around and see if the fuse blows. If it doesn't add one item at a time until it does blow the fuse. The last thing you added is where the short or high amperage draw is at.

 

[badsamaritan]

I disconnected all of that awhile ago, also disconnected the backup lights and transfer case switch as well since they are also on that circuit. No dice I used this thread as a guide

Heater Fuse Blowing

I have a 1973 FJ40. The heater fuse blew last week for the first time. I replaced it. It held for a day. Now it blows a fuse as soon as I turn the key to start it. That fuse also provides power to the following gauges: gas level,oil pressure and temp. I am sure it's a short somewhere. Thoughts...

forum.ih8mud.com

 

[1969FJ]

I disconnected all of that awhile ago, also disconnected the backup lights and transfer case switch as well since they are also on that circuit. No dice I used this thread as a guide

Heater Fuse Blowing

I have a 1973 FJ40. The heater fuse blew last week for the first time. I replaced it. It held for a day. Now it blows a fuse as soon as I turn the key to start it. That fuse also provides power to the following gauges: gas level,oil pressure and temp. I am sure it's a short somewhere. Thoughts...

forum.ih8mud.com

Do you have a trailer socket as I believe power goes there also. Also heater switches themselves.

 

[badsamaritan]

I do not have a trailer hitch, good call though, only switches connected are the hazards, headlights and ignition.

I know this sounds nuts but it really seems to be temperature based. Like something gets hot from all the driving and builds resistance?? It can sit running in my driveway all day with all the lights on and nothing happens....go for a 10minute drive and that fuse blows

 

[1969FJ]

I do not have a trailer hitch, good call though, only switches connected are the hazards, headlights and ignition.

I know this sounds nuts but it really seems to be temperature based. Like something gets hot from all the driving and builds resistance?? It can sit running in my driveway all day with all the lights on and nothing happens....go for a 10minute drive and that fuse blows

Have you ensured the fuse panel has good grounding to body ? I know this is a long shot, but the ignition switch feeds that fuse set.

 

[badsamaritan]

Is there supposed to be a ground that connects to the fuse block??? Right now is just bolted to the pillar, no specific grounds to or from the fuse block itself

 

[1969FJ]

Is there supposed to be a ground that connects to the fuse block??? Right now is just bolted to the pillar, no specific grounds to or from the fuse block itself

The ground is metal to metal from block to chassis. Sometimes resistance enters there.

 

[Engineer8000]

Since the heater fuse supplies the meter cluster, have you noticed any issues with the meters? If a sender or associated wiring was grounding, it would peg a meter and blow the fuse.

 

[badsamaritan]

Yes and no, I noticed the Ammeter never went positive. I added a ground wire to the VR to the frame and the Ammeter appears to be working. I also found a bad cluster light last night so I'll be fixing that today also.

 

[Cromagnon]

The fuse block is not grounded. Do make sure all of the fuse and wire contacts are clean and free of corrosion. This sound more like a movement issue than temperature. Sound like everything is fine while it is sitting still with the engine running but as soon as you start driving then the wires start moving and something causes a short and blows the fuse. You may be time ahead by pulling the wiring harness out of the 40 and do a really good inspection to see if there is any chaffing, exposed connector(s) or other anomaly. Intermittent faults are a bear to deal with.

 

[badsamaritan]

The harness is a fresh refurb from cooler man, it really hasn't been in the vehicle long enough to have any problems but I will add it to the list for sure......one thing I noticed on my drive is that the oil pressure gauge is starting to read rather high, it's not pegged but it's up there. This gauge is on that circuit I believe