Electrical Gremlins (1 Viewer)

[HMP]

1988 FJ62

Lets start on the stalk:
When I turn the headlights on then dash lights are basically gone. Like, it's VERY low, cant actually read the speedo etc when dark
And when I turn the headlights on the turn signal lights on the dash light up. Signals still work when you operate them, but the lights on dash stay on.

Fan blower / HVAC
Got nothing.
But when iI go to 3 or 4 (speed of fan) it starts making weird noise and causes the dash lights to come on if the headlights are off. BUt no blowing of air.


Ive turned the dimmer knob - that's not it.
I dont know yall, but I cant drive at night cause I have zero clue of speed or other gauges
I checked through the fuses on the dash panel today - they all looked fine

Any help is greatly appreciate

 

[SteveH]

Check your battery then check your alternator output at idle, speed, and under load (everything at full blast - lights, heater - idle and at 2000 RPM).

But, it sounds like you have a grounding issue somewhere. Any funky wiring under the dash by the PO?

 

[HMP]

Check your battery then check your alternator output at idle, speed, and under load (everything at full blast - lights, heater - idle and at 2000 RPM).

But, it sounds like you have a grounding issue somewhere. Any funky wiring under the dash by the PO?

Battery is brand new
Will need to get alternator checked

Yeah, maybe bad wiring by a PO
It used to work, then I got the issues right before I quit driving two years ago.
I dont know, but this sucks

 

[SteveH]

You can easily and effectively check the alternator yourself - it doesn't need to be removed and 'bench tested' by a drooler at an auto parts store. DIY is also free...

Since you mentioned 'bad wiring by PO' - check for any non-stock wiring under the hood and dash, and look closely at the battery terminals and nearby connections for corrosion or weakness.

 

[HMP]

You can easily and effectively check the alternator yourself - it doesn't need to be removed and 'bench tested' by a drooler at an auto parts store. DIY is also free...

Since you mentioned 'bad wiring by PO' - check for any non-stock wiring under the hood and dash, and look closely at the battery terminals and nearby connections for corrosion or weakness.

I did replace the battery cable ends, as the 'stock' ones were pretty boogered up, including a/the PO using a small screw between the post and terminals...
Ive got a lot of work to do, I'll be posting more pics as I go through things and trying to sort out some of these issues

I have to wonder if there's a bad ground or something within this system, something aint right

 

[dbleon]

Check all your grounds and also look for a voltage drop across the fusible link.

 

[diesellibrarian]

I have to wonder if there's a bad ground or something within this system, something aint right

These trucks have notoriously finicky grounds behind the instrument cluster. What you are seeing is what I and other have experienced: a bad ground causing resistance in one circuit that leads to problems in other circuits that share a common ground bus. Often it's headlights, signal lights, and instrument cluster lights that display odd behaviour. I'll see if I can find a photo of the common trouble spot.

 

[diesellibrarian]

That little orange connector is what was causing my problems. Several circuits ground there. I pulled the bottom off it, pulled out the multi-prong connector, cleaned it up, put it back in, and wrapped it in e-tape. No problems since.

 

[HMP]

View attachment 3787572

That little orange connector is what was causing my problems. Several circuits ground there. I pulled the bottom off it, pulled out the multi-prong connector, cleaned it up, put it back in, and wrapped it in e-tape. No problems since.

That's behind the dash?
While the dash is easy to take off (only a few screws), Im always cautious and hesitant to mess too much as the plastic is going to be quite brittle after 40 years.
But I'll try to get on it today

 

[diesellibrarian]

Yes, it’s directly behind the gauge cluster. Removing the bezel can be tricky - especially disconnecting the speedo cable - but if you go slow and don’t use too much force, you should be ok. It’s the right side of the bezel that is the most fragile and prone to cracking upon removal.