Electrical Problems From an Amateur / Guy Out of the Wrenching Game (1 Viewer)

[michaelharrisco]

Regarding 1978 FJ40 (generally stock)

Folks - this is the first post I've made in a really long time. While I still have the 40 and the 100 series, the reality is after getting older and having 2 kids I literally have not had to do any work (or have the time to tinker with it anymore) on the 40 in many years. It just keeps cracking with very little trouble...until now.

My hope is maybe something is really obvious to someone else that will help me, but if I can't figure this out I may have to take it to an electrical shop in town (there is a really good one about 15 min drive from my house).

Here is the order of events to where I am today:
1) Noticed the turn signals were intermittent (have been solid flashing for years)
2) Headlights quit working completly
3) Would still crank no issues
4) 3 days ago, would not crack at all (parking lights / dash lights still came on)
4) tapped the starter with a hammer and it cranked up
5) now won't restart
6) was thinking it was a starter (it still might be)
7) tonight...around 3 days later no lights / she is dead completely
8) I have a rebuilt starter, but was not aware how different the configuration is (wire harness, size for mounting, etc)...aka this does not appear to be an easy R&R. I'm not familiar with the high torque replacements which this probably is.

I tried jumping, but doesn't seem to be doing anything (lights not coming on at all).

All fuses visually look good (I may replace all of them with new just to rule that out).

Seems like trouble for my rusty 40 maintenance skills since its been a while and I'm way better with mechanical repairs than electrical.

With all that said...any advice?

 

[CruisinGA]

battery voltage (use a multimeter)?
condition of battery cables, terminals and grounds?

 

[michaelharrisco]

battery voltage (use a multimeter)?
condition of battery cables, terminals and grounds?

I'll check tomorrow, but battery is new (this year) and cables and terminals are good. The grounds? Um, not sure and honestly never messed with them / know where to check on grounds. I'll look around/search tomorrow.

 

[charliemeyer007]

Starters that need a hammer blow are on there way out.

With the battery unhooked take a wire brush to the terminal brackets in the fuse box - a 30 call bore brush is just right. Go to every to every electrical plug/switch - pull it open ( be gentle its old plastic) and clean the contacts on both sides of each half of the connector. Needle file, small piece of crocus cloth; then spray it contact cleaner, shake/blow dry and then use some dielectric grease on the contacts.

You can add a new ground wire from the neg terminal of the battery to a screw/bolt on the firewall.

 

[Chungas Revenge]

All solid advice ^^^^. Grounds, terminals, dielectric grease etc etc.

If you have a new battery something’s killing it. IE it’s not getting a charge.

Alternator putting out a charge? checked your Voltage Regulator? My 76 is externally regulated (voltage regulator/VR). Is your 78 still in the stock charging configuration? Externally regulated or was it converted to an internally regulated alternator? If it’s still stock look for the VR. Should be mounted on the drivers side fire wall and look like one of the pictures below (Pirated from MUD) Have a look at your FSM for clarification on what type you have (Different type plugs). You can remove the black cover and have a look at the condition. If it’s badly corroded it may be INOP and need replacing.

Edit: Check your fusible link while your running down your checklist. And check the ground cable on your starter. If you don’t have one, add one.

 

[Sky King]

I once bought a van off a guy back in the 80's that had chronic electrical problems. It had been to several repair shops with no luck. I got it cheap and the first thing I did was clean EVERY ground connection on it down to shiny bare metal both frame and body on both parts of the connections. After that it was trouble free for all the years I owned it. I've done the same with any old project truck I've brought home as they have had corroded ground connections due to age and humidity. I agree with the the other comment on the starter if it needs a whack with a hammer but when you are replacing that take a hard look at your battery and starter cables. Are they in good shape? Are they of sufficient gauge to handle the amperage they will need to carry and to go full circle with this does the battery have a good clean ground connection on the frame? My last thought on this is that on some trucks I have added a heavy gauge ground wire from the frame to the body because the factory never did, that was OK when new but age and corrosion created electrical resistance that the heavy gauge jumper wire bypassed.

 

[45Dougal]

Sounds like you have a couple of things going on here.
Check your battery terminals are clean and well seated.

Starting at the beginning, you had two electrical issues (headlights and turn signals) which both run on different fuses.
Firstly, buy a digital multimeter - they're so cheap that it's pointless not having one.

Start by replacing all fuses and cleaning the fuse box front and rear.
Test for 12V on both sides of each fuse (black probe always to ground/chassis).

If it cranks but won't start now, it's possible that the coil got damaged if it was left switched on ign for a long time while you were trying.
Add some photos and you'll get clearer advice

The cranking issue could actually be the ignition switch (which could also explain your turn signal issue) - worth jiggling it all about a bit and checking the connector block under the column.

 

[Chungas Revenge]

Sounds like you have a couple of things going on here.
Check your battery terminals are clean and well seated.

Starting at the beginning, you had two electrical issues (headlights and turn signals) which both run on different fuses.
Firstly, buy a digital multimeter - they're so cheap that it's pointless not having one.

Start by replacing all fuses and cleaning the fuse box front and rear.
Test for 12V on both sides of each fuse (black probe always to ground/chassis).

If it cranks but won't start now, it's possible that the coil got damaged off it was left switched on ign for a long time while you were trying.
Add some photos and you'll get clearer advice

You make a good point. Power in - Power Out at the fuse block. Pics will defiantly help.

 

[kerplunk]

Starter needs to have a heavy positive cable straight to the battery on a large "lug" (i.e. nut) and a single smaller blade style connector in a plug going to the ignition switch.

There might be some other wiring, depending on the year and changes made by the owner on other wiring *around* the starter, I'm vaguely aware of some having the "white" wire to the ampmeter / fuse panel connected to the battery via that starter cable. But this should all be pretty straightforward issue of just keeping other stuff connected the way it already it, clean it up while your at it, but don't change it...

Old and new gear reduction starters are about the same with the battery lug and the wire to the switch, they'll just be different locations on the starter, but pretty obvious what they are.

And commonly, on the bolts holding the starter to the engine, people put ground cables on those bolts. Clean and inspect the terminals, make sure the copper isn't getting all green inside the terminal and insulation. Clean whatever's underneath that terminal (i.e. starter ear) so there's no paint or rust. Reattach is all the way you found it.

But the lights, all the other issues you've mentioned are typically bad grounds. (hitting the starter with a hammer is the starter....) And, if nothing's working, start at the battery, pull the negative cable, clean the terminal, clean the post, inspect for corrosion inside the terminal / inside the wire. Follow that ground / negative battery terminal to the frame / block / wherever and pull it off, inspect and clean. If there is a big cable on the starter mounting bolt, clean inspect the other end, or look for wires attaching the block to the frame and frame to the body, clean and inspect....

A bit of corrosion under these cables can cause a world of misery. And a lot of the wiring isn't steel (copper or tin) so the corrosion isn't going to be typical rust, but if it looks rusty, it's not good. And it could possibly be some corrosion in the positive side of the system, i.e. fuses and switches, but intermittent blinkers tends to be the first thing showing up with a bad ground.

 

[michaelharrisco]

Still interesting.

Check list completed:
Confirmed batt is good (multi meter and a tester)
Alt measures good
New fuses installed
Checked grounds and appear clean and tight
Voltage reg seems perfectly clean (did remember pic of that)
Used bypass crack trigger (can’t recall proper name) connected to batt and starter…it would turn over but never could get it to stay running. This shows it’s not a bad starter to me.
Sprayed carb cleaner
Cleaned spark plug and confirmed spark
Confirmed gas going into carb
Carb mechanics seem good


After all that still can’t run parking lights or anything else even with measuring good battery.

Battery terminals are spotless and retightened.

My gut (after talking to really good car guy across the street that took a look with me). Is it might be wiring in steering column. Def bad ground somewhere but I’m not sure I’ll be able to find it.

What is this oem part pictured “igniter assembly” on top of the coil? We looked at that wiring and it seems okay, but I also moved that around the other day when it magically cracked last. Wondering if I moved something around there that allowed it to crank?

Odd to me all electrical is out and I can’t get it to idle with a key switch bypass?

With all those checks done any fresh ideas to try?

FYI I’m gonna be away from truck for 4 days starting tomorrow afternoon so might be delayed on responding.

 

[kerplunk]

Voltage reg seems perfectly clean (did remember pic of that)

If there was a problem with the voltage regulator, it would either prevent it from charging the battery or overcharge and burn up the battery. I don't think either is a problem you are having?

Odd to me all electrical is out and I can’t get it to idle with a key switch bypass?

The idle solenoid on the carburetor need to have power to open and allow gas in. Should be one wire going to the carb.

Is it might be wiring in steering column. Def bad ground somewhere but I’m not sure I’ll be able to find it.

There is nothing grounded in the steering column I'm aware of?

Power comes from the positive post on the battery to (usually) a switch, to the load (i.e. accessory) and then to "ground" (the chassis) and using the chassis as a bus, back to the negative post on the battery.

The only things in the column are switches. And while the ignition switch is a possibility I don't understand how it would impact the lights. I know on earlier models (maybe yours also) the ignition switch is connected with 4 wires and there's a plug right behind the dash where the column goes through / under it. You can disconnect that plug, one pin should be 12v+, one goes to the starter, the other two, following a wiring diagram for a '74 show one going to the wiper fuse and the other split between the heater (fan), turn signal and ignition coil fuses....

So, this leads me to ask if the fan works?

How about the horn? Ignition switch shouldn't cause the horn to fail, so if that stops working with everything else, probably something else.

Test for power at each of the fuses, ignition on and off, fan, turn signal and IG coil fuses should have power with key on and not with the key off. If not, find that plug and see if there's 12v+ on one of the pins.

Used bypass crack trigger (can’t recall proper name) connected to batt and starter…it would turn over but never could get it to stay running. This shows it’s not a bad starter to me.

You mentioned hitting it with a hammer? That didn't fix anything in the wiring harness. It might be coincidence and something else failed and started working, or it going to fail soon...

 

[45Dougal]

It sounds like you don't have power anywhere.

It certainly doesn't sound like a bad ground to me - that is sadly rolled out as probable cause for every single electrical problem on here that is not understood, and is extremely unhelpful to finding the actual problem.

Did you test voltage at each side of each fuse?

This will tell you if you have power to the ignition switch and also power from the ignition switch when switched on.

My guess is that your ign switch is either worn out or has bad connections, or your ammeter cable has come loose or burnt through.

Testing voltage on both sides of all fuses wrt ground will tell you if either or both are working.

Does your ammeter move under any circumstances now?

 

[michaelharrisco]

Good responses and yes it appears power is going to nothing!

I forgot to check power across each fuse.

I’ll have to get back on these checks on Sunday.

Stay tuned and if anyone else has any other checks / good advice I’m all ears. I plan on giving this a few more attempts but after a few more tries I hate to say I may have to get it towed to electrical shop (I trust).

 

[South Texas 97]

take the plastic surround of your steering shaft and check that you are getting 12volts at your key - that you can turn it over with a remote start, but not keep it running - could be the ignition switch.
I am sure you already have a wiring diagram, so you can see when you turn the ignition switch to it's different positions, which wires should go live.

connectors can get the green crusties - even though they look ok.
Same with the connectors on the back of the fuse block.

 

[peesalot]

Main power from batt to starter to amp meter then fuse panel is good ? If not, at which point in that order does power disappear ? If fuse panel has power but some things dont work then it is a switch, ground, device issue, fuse panels known to corrode on back, check that. FWIW when they sit with low voltage these things seem to creep up. Personal experience, even tho those fuse terminals look good, remove wire both sides, clean/check, remove fuse, clean and clean the fuse tabs as well. I seen them where you could just barely rub it and whamo all good. I have no idea about the igniter thingy, replaced all that with LS.

 

[Engineer8000]

Check the fusible link(s) and connectors for continuity.

 

[Coolerman]

You need to check the FUSIBLE LINK as has been mentioned three times!
The fusible link connects to the positive battery terminal. It's job is to protect the charging circuit 10ga wires.
Here is the path this takes: From battery + through the fusible link, into the solid white 10ga wire coming out of the main harness near the battery, and routes to the Amp Meter + terminal. Then through the Amp Meter, out the - Amp Meter terminal where it turns into a 10ga White/Blue wire and goes to the alternator B+ terminal.
If your fusible link is bad you will have NO power to the fuse panel. Also if your Amp Meter is bad your battery will not charge as that circuit will be open. You can just short to two Amp Meter wires together to get going.
I sell new fusible link kits that include the fusible link, the battery side connector and a new harness connector and terminal. Click on the link in my sig line to go to my web site.

 

[michaelharrisco]

Looks like I’m missing fuse link or this is bad? I’m gonna rip into this but might be placing an order soon.

 

[kerplunk]

Looks like I’m missing fuse link or this is bad? I’m gonna rip into this but might be placing an order soon.

Probably, but it's kinda hard to really tell from a picture.

I did a bunch of searching for information on it earlier this summer and found very little. Rumor is that it should be -2 on the AWG numbers higher (i.e. smaller wire) than the circuit it's protecting, but have much thicker insulation (so that the conductor can burn up without starting a fire).

(and a specific length).

Picture doesn't really look right, but could be the actual right kinda wire, wouldn't really be able to tell without seeing an end of the wire stripped. (and even then, mostly guessing).

If you are having issues, and especially doing work on it, you really should make sure there's something there protecting the harness for burning if there's a short. Long term, Coolerman's fusible link is basically the original solution. Just for working on it, I would rig up a fuse holder with a 10 or 20 amp fuse just to prevent shorts for testing (and totally unplug it while actually stripping / crimping / etc.), just the lights, or just one accessory on at a time should stay under 20 amps draw unless it's shorted.

BUT, your original problem, that's probably not the cause... If you've got +12v on white wire on the stud on the back of your alternator, this isn't your problem. It is a safety issue, but wouldn't prevent lights from working.

 

[michaelharrisco]

Here is the wire ends. There is no fuse anywhere and it’s been like this for as lonng as I’ve owned it 10+ years. At this point I’m gonna put it back together and see if I can confirm V getting to white cable.