Under Dash Wiring

Up until now everything was working fine. Now, when I switch on the ignition I get nothing, no dash warning lights, no cranking starter. But... A faint smell of something burning. All other electrics (headlights, horn) work fine.

So I climb under and have a look to see everything looking normal; no disconnected, melted or bare wires. By touching a few I can feel the red wire from the ignition switch is warm. Turning the ignition on without cranking the starter I get the same warm wires. Suggestions? I have the FSM, but the wiring diagram is not color coded and the wires all feed into the loom.

It's my 69 CJ5 with F134, 12 volts with generator, if that makes a difference. And the battery is holding at 12.25 V.

Thanks!

 

You might have a short.

 

Not that it is likely the cause of your problem but 12.25V is only about 50-60% charged. You want to see at least 12.6V in a fully charged battery.

 

Okay, sounds like I have my work cut out.
Disconnect battery - check!
Put battery on charger-check!
Chase down possible short... Hmmm, not sure the best way to do this, other than the obvious "look for wires touching stuff they shouldn't be touching". Is there a more efficient way to do it?

I'm pretty sure it's under the dash, since earlier in the week I stuffed the dangling heater motor wires (which are much longer than they need to be!) up over the steering column. I didn't think of that as a possible culprit, since it's become a regular occurrence about every other month when the dangle down by my feet on the pedals. It would be pretty easy to knock something else out of place while doing that. I guess I should come up with a more permanent/neater solution to that problem.

 

Get yourself an inexpensive digital multi-meter. The greek symbol Omega is for checking the resistance of whatever is between the probe tips. Do not do this with circuits energized. The meter will display how many ohms of resistance. With battery disconnected you would be hunting for a low reading with the key on, indicating a short circuit.

Keep in mind that some equipment may correctly display a short to ground if a switch is on. For example if you pull on the headlight you have completed an energized path to groung through the switch and headlight filaments. Same with heater blower motor. Make sense?

There is often another position on meter that gives audible beep for a short circuit, which is convenient when rooting around under a dash.

Chilly

 

I suspect if you start with visual inch-by-inch tracing of wires you'll find the issue. Something pulled loose and is bumping a ground path, or brittle insulation cracked and is exposing a hot lead to ground path. Seems like youve assaulted some wites regularly so that may be it. Check under-hood wires that arent neatly tied up that may have melted to a manifold.

 

just one more question . does jeep have a amp gauge

 

Bad ignition switch? Poor contacts making high resistance = heat. Is the switch hot?

 

Remove the distributor wire from the coil before troubleshooting your electrical gremlins. You may already have burned up the points in the distributor. I would start by determining why it won't crank the engine over first. Starter solenoid, ignition switch and the wiring associated with this system.

 

Jammed starter motor.
Look where the wire loom passes through the dash. If that grommet is torn or gone, then your ground source may be there.

 

This 'started' to happen to me. Horn went off and smell of smoke in the air. It was at the firewall (wire touching body) - so that should get checked out too (although by now you probably already have).

 

Hopefully nobody installed this. Not compatible with Kaiser smoke.

 

Will it fix a Harborfreight inverter? My buddy's sprung a leak real bad.

 

No ameter gauge, just the light.

Sounds like I need to dive back under the dash and have a good long look first. Or maybe I'll carefully tape the heater wires out of the way so I stop assaulting the wires underneath! Good suggestions.

Oddly I did have the starter jam a few years back when it decided it didn't need all its teeth on the bendix! When that happened I recall I did still have the dash warning lights come on, unlike now.

(I like the jar of wiring harness smoke, by the way. Made me laugh out loud!)

Okay, I have my working orders, wish me luck. And thanks again for the pointers.

 

I need some smoke for my heater motor!

 

X2 regarding the switch; peace of mind regarding safety and even theft. Hope you get the wiring problem figured out. My experience is that a little time, patience, and a few beers is all that's needed to chase down the problem. Not only do the stock wiring and accessories deteriorate over time, but gremlins from previous owners have a way of showing up. Similar to what others said, I'd start at the switch and look for obvious issues such as chaffed wires, scotch locks ( I hate those things), weird connections such as wire nuts and poorly crimped terminals. I'd certainly follow the wire that you described as "warm" and see what it leads to. The chiropractor bills will be well worth the effort of laying under a the highly cramped dash. Don't forget the beers; very important.

 

So doing this! My neck is still out from the last time contorting episode, lol!

 

try doing it laying on back with dog on stomach . no seats or brackets . just a thought . every time I have transmission out . I say to self . man working on dash would be easy