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Discussion Starter · #1 ·
‘96 Bronco, Eddie Bauer, 5.8L

So, I’ve read countless posts, articles, etc. I’ve fallen into so many rabbit holes I can’t begin to count them. I’ve decided to post a detailed description and see if anyone else has experienced this rather unique power system problem:

1. New alternator, problem persisted, I returned and swapped. Problem persists.
2. Same with battery.
3. Cabling all appears to be in good condition, from what I can tell.
4. Previous owner put an aftermarket stereo and aftermarket tow brake controller, so, there’s that.
5. Lastly, my transmission is failing (more on that in a moment).

Here’s the problem I’m experiencing:

Bronco will fire up, and run great.

About 45 minutes into a drive (gently driving because I’ve yet to replace the transmission), something trips and my OD light on the shifter starts to flash. As I said, I’m aware that the transmission is failing, so generally, this is redundant for me.

As soon as this happens, my blinkers stop working, my voltmeter goes hella low (like, close to 8 or 9), and very, very slowly, I start to lose electrical power. Clearly, the alternator is unable to charge the battery at this point.

Here’s what’s super strange: when I stop, of course she won’t fire back up. All the symptoms of “dead battery”. But...if I leave her sit for a few hours, she fires right up, voltmeter shows normal voltage, and everything really works normally. Except for my sad, sad transmission, of course.

One more note: my speedometer has wobbled for a long time, and I’ve just neglected to troubleshoot. I assumed it had something to do with the failing transmission, since my understanding is that sensor is on the transfer case.

When this thing happens, eventually, my speedometer just stops working. Not sure if that’s related or not.

And that’s it. As long as I keep it to short drives (which I normally do because of the impending drivetrain failure), everything’s great. But I do periodically have to very carefully take her on a 1.5 hour commute, and that of course brings this problem back to the forefront.

Any ideas? I’ll wrench on my bronco whenever possible, but I’m NOT a mechanic. I’m not even sure if the voltage regulator is external on a ‘96? Or is the alternator diode external?

Anyway, any thoughts would be helpful. Especially if you’ve experienced something like this before.

Thanks!
 

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90 Bronco. 302 EO4D, not lifted yet, 33's, Kick Ass Stereo.
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I have not experience this before but I have worked on electrical systems for a long time. It sounds like you have a bad connection. When the engine gets hot the connection starts to fail and you end up with your issue. then when it cools off...presto contact good again for a while. I would suspect a the ground cable but any one of the cables could cause the issue. I would replace the cables and make sure to clean the spot where they are connected really good to assure good conductivity.
 

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'92 Custom w/ '95 MAF 5.0 M/T, 33's, 4.10 LSD
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Lots of electrical gremlins in conjunction often points to PCM problems. The capacitors start leaking and mess up tons of stuff. I've seen some where it only happens when heat is generated (i.e., with the vehicle running for a while), resulting in nearly-rotted through traces on the board losing their signal.
 

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Yo Danial James,
WELCOME!
E4OD Transmission Control Indicator Light (TCIL) is a LED and overdrive on/off switch at end of the Transmission shifter stalk; flashing OD light is an indication of a transmission related trouble code in the Powertrain Control Module (PCM).

Borrow an OBD II SCAN tool from local parts stores under their loan-a-tool program with refundable deposit post codes found.
168213


168211

●Cables that appear overheated and/or discolored indicate the need to thoroughly test all ground connections.
Here are the grounds, plus some others thrown in the oven with the turkey; inspect battery negative terminal to block, then to frame.

G100 location (On core Support Left (Drivers) Side)


by jowens1126


G101 Alternate location is @Passenger side Fender next to the battery
by jowens1126

G200 pic in lower side of passenger side plastic kick panel with green screw.

Pic is titled, "1356 Electric Shift Control Module Location pic; "...The module I MIS-labelled as "Airbag" is actually the Wiper Control Module (WCM). The Airbag Diagnostic Module (ADM) is light blue, wrapped in black foam, above the gas pedal..." Ryan M pointed out the error.

G201 location (Drivers side kick panel)

150691

by BeastBronk



G103 location (on engine block)


by jowens1126


G104 location (Drivers side Fender near firewall next to diagnostic connector)

by jowens1126

Frame Ground location (Passenger side Cross member above engine mount)

by jowens1126


G101/102 near battery on inner fender pic @




by SeattleFSB
 

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Discussion Starter · #5 ·
Wow...y’all are seriously fantastic.

Sounds like I got some troubleshooting steps to go through, this has provided so much clarity for that process!
 
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