Removed Speedo cluster, now won't start

[First73]

I just removed my speedometer cluster and sent it out to be reconditioned. When I just tried to start my Bronco, I got no response at all from turning the key. I'm a new classic Bronco owner but have to assume some/part of the ignition system runs through the cluster. Can anyone confirm this? Is there a way to get it running without the cluster in place?
Thanks in advance!

 

[tasker]

automatic? maybe not in park?

 

[First73]

automatic? maybe not in park?

Thanks for the reply. It is an auto, and it is in P. I've gotta go check that when I was removing all of the wiring for the cluster I didn't yank one from the ignition......

 

[chuckji]

If you still have the original wire harness, there is a large gauge wire (black w/green stripe?) that has a disconnect in it right at the meter (to allow a way for the wire to pass through the Ammeter current sensing loop) - make sure those were reconnected together.

 

[chuckji]

This wire circled in Yellow.

 

[DirtDonk]

Exactly.
Oh, and it’s a yellow stripe. So the largest gauge wire in the area, black with a yellow stripe. It’s the primary power for the entire truck.
It’s essentially a single loop of wire from the BAT output of the alternator, through the cabin and instrument cluster (ammeter), then back out to charge the battery.
But in the meantime, when you separate that plug, you disconnected the fuse panel and ignition switch from the battery. Rendering virtually everything on the truck dead.
Or at least those circuits critical to turning most accessories on.
As mentioned already, find the two halves of that connector and re-attach them. Making sure that they are clean and rust free first.
Make sure they are also tightly snapped together.

 

[dmoses42]

Mini-hijack question... If I'm switching to a 3G alternator, to disconnect the ammeter from the circuit, do I just disconnect that plug and remove the wire from the loop on the ammeter and plug it back together or do I have to move the wire farther from the loop to keep it from sensing it? Sorry for the hijack...

Don

 

[First73]

Exactly.
Oh, and it’s a yellow stripe. So the largest gauge wire in the area, black with a yellow stripe. It’s the primary power for the entire truck.
It’s essentially a single loop of wire from the BAT output of the alternator, through the cabin and instrument cluster (ammeter), then back out to charge the battery.
But in the meantime, when you separate that plug, you disconnected the fuse panel and ignition switch from the battery. Rendering virtually everything on the truck dead.
Or at least those circuits critical to turning most accessories on.
As mentioned already, find the two halves of that connector and re-attach them. Making sure that they are clean and rust free first.
Make sure they are also tightly snapped together.

@DirtDonk @chuckji
Thank you for the info. You were spot-on, the truck started right up! Would this be a good spot for an ignition kill switch?

 

[Broncobowsher]

Mini-hijack question... If I'm switching to a 3G alternator, to disconnect the ammeter from the circuit, do I just disconnect that plug and remove the wire from the loop on the ammeter and plug it back together or do I have to move the wire farther from the loop to keep it from sensing it? Sorry for the hijack...

Don

You are chasing the wrong problem. The Bronco ampmeter is inductive. Doesn't suffer the burn out issues that full pass through amp meters have.

The real problem with upgrading the alternator is the wiring isn't big enough to handle the added current. Bypassing the amp meter does not fix the undersized wiring issue.

 

[DirtDonk]

And by that, what he means is you connect it like any late model high-power alternator. You leave the black ammeter/charge wire in place on the starter relay, but you do not use it’s other end with the new alternator.
You make or buy a heavy gauge cable and run it directly from the new alternator’s output post, over to the battery.
Or, as is the most common practice, just to the starter relays battery post.
As for what to do with the end of the old wire at the alternator, you can either cap it off, cut it off and cover it safely, or move it over to the fender and connect it to a power stud and use it as an auxiliary power supply terminal.

 

[dmoses42]

You are chasing the wrong problem. The Bronco ampmeter is inductive. Doesn't suffer the burn out issues that full pass through amp meters have.

The real problem with upgrading the alternator is the wiring isn't big enough to handle the added current. Bypassing the amp meter does not fix the undersized wiring issue.

While I don't want to do a major hijack on the OPs thread, can you take a look at this and make sure I'm on track:

Got a Mega Fuse harness from a 98 F150, also has a 20 amp fused Yellow/White wire and the Green/Red wire to use.
- Unhook Voltage Regulator, take Yellow wire from connector, attach to Yellow on Mega Fuse harness. Take Green/Red wire from connector, attach to Green/Red on Mega Fuse harness.
- Remove Orange wire completely. Cap Black/Red and Black/Yellow.
- Put Mega Fuse harness on B+ starter relay terminal to B terminal on the Alternator.
- Leave the Ammeter alone until I convert to Voltmeter.

I just wasn't sure on the Ammeter because I couldn't find a definitive answer.

Thanks again, and sorry again for the hijack...

 

[DirtDonk]

Leave the 10 gauge wire, not sure if it’s black with red or not, connected to the battery side of the starter relay.
The relay post gets pretty busy at about this point. What with the battery, the alternator charge wire, and the cabin power wire all connected. And sometimes even the yellow wire from the horn relay, if you have a 74 or later.

 

[dmoses42]

Leave the 10 gauge wire, not sure if it’s black with red or not, connected to the battery side of the starter relay.

The one coming out of the cab correct? Should already be connected to the relay? I forgot to mention that one. No horn relay, mine's a '72.

 

[dmoses42]

I've gotten most of my info from Steve83's wiring diagrams. The Black/Red to cap off appears to be a ground from the alternator to the voltage regulator in his wiring diagram, and it has a Black/Red coming from the cab to the starter relay.

 

[DirtDonk]

Black with red is the ground color (sometimes), but black with red is also sometimes used for that main power wire.
But on most early Broncos, if I’m not mistaken, at least up to about 75 or so, it was just black. No stripe.
Yes dmoses, that’s the one I’m talking about. Leave that one connected to the starter relay because that supplies power to the rest of the vehicle.

 

[dmoses42]

Ok, Thanks, Paul. All the rest I listed looks good then? If so, that's what I'm going to plan to do.

Don

 

[DirtDonk]

Yes. As long as all of the wires you mentioned en up in the new alternator connector so they can do their jobs, you should be good to go.

Because this harness is living in one of the more harsh environments of the vehicle, just make sure that any and all splices that you make are perfect. Clean, tight and waterproof.

 

[dmoses42]

Cool. I'm doing the switch from 1G to 3G at the same time as the DS2 upgrade. And I'm good on the "clean, tight, and waterproof" front. I redid a Explorer harness (following EFI Guy's videos) for the '73 I sold, during the COVID hibernation, and while I didn't switch it to EFI before I sold it, I got good at butt connectors, solder, and adhesive lined heat shrink. I'd probably use that harness on my '72, but I built that harness for a 4R70W and when I get to doing the drivetrain for my '72 its getting an AX15. I just want to get it moving under its own power for now...