Author Topic: Electrical Gremlins. (Read 9404 times)

Nightpath · « **on:** September 16, 2014, 01:18:51 PM »

So I've been patiently awaiting my swap and I've been ironing out bugs.

Some of my last are the most mysterious.

At random times the car runs like crap. I'll get out, work for a bit then go home as if it ran fine all the time.

The headlight switch whines when it's off. I've replaced it and it still whines.

The tach is a crap shoot. When the car runs fine so does it. When it acts like an

the tach does too. When running bad of I use the signals it will jump up 500 rpms then back, or will start working with the brakes pressed.

And the radio randomly resets back to factory when the car is turned off. If I power it up it usually has the saved setting but when I start it the radio resets.

It does a few other odd things, like the wipers randomly stop (new switch, have yet to install the new motor).

But yeah, it's a random problem. I just went 2 weeks without a issue.

carnuck · « **Reply #1 on:** September 16, 2014, 11:11:29 PM »

Sounds like a loose battery cable.

Nightpath · « **Reply #2 on:** September 17, 2014, 09:39:29 AM »

There is that possibility, but I don't think it is. I was thinking a bad ground possibly.

I DO have spare cables I might swap in to see if it makes a difference.

It is odd that the tach will work fine, then bump to nothing and only show RPM's when the signal light or whatnot is turned on.

Hmmm....

Mernsy · « **Reply #3 on:** September 17, 2014, 11:30:34 AM »

Check, and re-tighten the ground point on the firewall between the brake booster and the engine. It also doesn't hurt to run extra grounds between the engine and inner fender, engine and firewall, inner fender and firewall, etc...

carnuck · « **Reply #4 on:** September 17, 2014, 12:52:21 PM »

I was thinking ground cable to the body and forgot that word when I replied.

Nightpath · « **Reply #5 on:** September 17, 2014, 02:14:50 PM »

I'll check those grounds, might not be there at all. But I might get slack AND lazy since the new motor is going in in a few weeks, so I can add all sorts of grounds when I do that

Nightpath · « **Reply #6 on:** September 18, 2014, 09:14:38 PM »

I don't see a bonding cable between the brake booster and engine. Any pictures of where is at so I can add one?

Mernsy · « **Reply #7 on:** September 19, 2014, 01:07:25 AM »

Look for small black wires screwed to the firewall between the brake booster and the engine. It's a place where wires are grounded to the firewall. Not sure what a bonding cable is??

Nightpath · « **Reply #8 on:** September 19, 2014, 06:01:17 AM »

It would be the same thing. Those braided cables in the engine bay are bonding cables. Anything that grounds is a bonding cable. Just a different name for them.

Any pics of the screws? I see no wires at all

Mernsy · « **Reply #9 on:** September 19, 2014, 08:33:04 AM »

You can see my SX/4 has only one wire. My sedan has three, I think.
You can see a bit of the brake booster in the lower right hand corner.

(I hope the mods can archive this pic as it seems to be a very hard to find ground point.)

Nightpath · « **Reply #10 on:** September 23, 2014, 11:37:34 AM »

All the grounding points in the engine are there, and cleaned.

Issue still happening though. I can turn the key off and on, the radio has settings saved. Soon as I crank the engine it resets.

Mernsy · « **Reply #11 on:** September 23, 2014, 12:03:35 PM »

Where does the radio get its power from? Trace it back and change it.

Nightpath · « **Reply #12 on:** September 23, 2014, 01:28:43 PM »

I have the power source hooked right into the fuse box (fused of course)

Mernsy · « **Reply #13 on:** September 23, 2014, 02:14:15 PM »

You should have two power wires. One for the radio itself and one for the memory. Are they both hooked up at the same place?

Nightpath · « **Reply #14 on:** September 23, 2014, 07:58:53 PM »

That's the thing. The radio memory will randomly save. It's absolutely random.

The main power wire (which on my radio) is threaded right to the fuse box with the proper fuse in line. IIRC that wire is also used for the memory.

carnuck · « **Reply #15 on:** September 23, 2014, 09:02:58 PM »

So it has a loose connection?

Nightpath · « **Reply #16 on:** September 24, 2014, 06:03:10 AM »

Funny but that never occurred to me. I've looked for missing, burnt or corroded but not loose. Now I have to figure what would be common in ALL the interior electrical.

Nightpath · « **Reply #17 on:** September 25, 2014, 01:12:47 PM »

I'm at a loss now. All the wiring is tight and seems to be solid.

I'm almost betting on a relay / fuse / circuit somewhere that's bad. I'll pillage one of the old Eagles for all of those and swap them out.

I have noticed that my starter solenoid has a spark fly off it when I start the car. Almost betting that the starter needs to be cleaned and the mounting bolts grounded properly.

Nightpath · « **Reply #18 on:** September 25, 2014, 03:29:01 PM »

My starter had a few problems. Wasn't grounded right, dirty as heck, etc.

I've confirmed that electrical resets when I crank the engine. All electrical.

Any ideas?

carnuck · « **Reply #19 on:** September 25, 2014, 04:05:39 PM »

I just added a new ground from my battery to the body (in my MJ) last night and my headlights are MUCH brighter now!

IowaEagle · « **Reply #20 on:** September 25, 2014, 04:32:26 PM »

Grounds are important, specially with these high draw autolite starters. And, an extra ground to the body is always good.

Nightpath · « **Reply #21 on:** September 25, 2014, 08:02:13 PM »

A friend told me that there's usually a ballast resistor somewhere in the ignition system (besides the one on the stock coil).

Right now the starter is sucking all the current when it starts.

Any ideas where I can find this mystery dohickey?

carnuck · « **Reply #22 on:** September 25, 2014, 10:50:49 PM »

Ballast resistor will affect ignition and not much else. (it'll die when it goes bad) Most of the Gauges are controlled by a 5Volt regulator in the temp gauge.

Nightpath · « **Reply #23 on:** September 26, 2014, 07:11:05 AM »

I'm suspecting that the starter is bad. Sure it starts the car but only when it comes into play does everything reset.

Might pull a few other starters to see what happens. Won't hurt.

carnuck · « **Reply #24 on:** September 26, 2014, 01:13:12 PM »

See if someone has a clamp on ammeter to check the draw when cranking. If not that, then a voltmeter to make sure the battery isn't dropping below 10 volts (minimum needed) while cranking. If it is, probably the nose bushing in the starter is toast. I'm switching to the later style flexplate and running the shorter 4.0L starter.

Nightpath · « **Reply #25 on:** September 26, 2014, 01:35:22 PM »

When I looked at the starter I noticed the metal lid on the casing (that hides the moveable part that initiates the starter) was lifted, and so full of crud it almost made me wonder how the living heck it even still worked.

I do get a spark on my solenoid at the starter cable each time I start it. This alone tells me there's something feeding back through something.

Going to hit the graveyard and pull a few starters, see how things go

carnuck · « **Reply #26 on:** September 26, 2014, 01:50:01 PM »

If there is an arc where the cable bolts on, it means the connection is corroded or loose or both. Sometimes the crud builds up between the tin cover and the starter stud which can cause a short too.

Nightpath · « **Reply #27 on:** September 26, 2014, 06:54:17 PM »

It's at the solenoid which is brand new and the cable is brand new. I didn't see it happen when I was looking for it this afternoon.

And my battery is dropping below 10 volts when the starter is engaged but it happens too fast to see just how low it's going.

I'll check it tomorrow when it takes a few long cranks to start.

Mernsy · « **Reply #28 on:** September 26, 2014, 09:59:38 PM »

Pull the coil wire and it will still crank but it won't start.