Power Distribution Box for '84 Ford Bronco? [Archive] - FSB Forums

: Power Distribution Box for '84 Ford Bronco?

10-25-2012, 10:53 AM
Hi Folks,

I have a 1984 Ford Bronco with the 351w and four speed manual transmission. It was running great until last week when I was trying to change the battery in the rain and as soon as i put the negative cable on, it started sparking profusely and my solenoid was smoking. After replacing the solenoid, battery, and voltage regulator, checking all the fuses in the fuse box under the dash, I tried to turn the key and I got nothing. No lights, no ding, absolutely nothing. As a matter of fact when I put the cables on the new battery, it wont spark at all, even if i tap on the terminals with the cable. Is there a power distribution box or relays in the engine bay I should be looking at that would cause something like this?


10-25-2012, 11:23 AM
Yo B,
Was starter turning over when solenoid (starter relay on inner fender) was smoking?
Check Fusible Link between the starter relay and alternator
Bad FL pic Ron Francis via Ryan M (Fireguy50) at http://oldfuelinjection.com/files/fusible-link-blow.pdf
Bad Fusible Link pic & depiction; "...most fusible links have melted/charred insulation when they burn out..." by miesk5 at http://fullsizebronco.com/forum/showthread.php?t=181223
see more including:
pics by shift1313
here are some pictures i just took. the first two pics are of an 89 5.0. because of the loom i wasnt able to trace the wires for you. The second pic is at the starter relay to show you a fusible link wire(the green wire in my fingers you can see at the eyelet there is a black plastic block). the third pic is of my 85. i think that big block is another style fusible link ford used on older stuff(but im not sure).

Wiring Diagram in an 84 Bronco & F Series Section 2
Source: by Chilton http://content.chiltonsonline.com/content/images/8576/images/85766114l.gif
Location in Wiring Diagram for 84 Bronco & F-Series; "...Similar to 80-91 Bronco
http://www.supermotors.net/getfile/714912/thumbnail/wiring84.jpg (http://www.supermotors.net/clubs/superford/registry/media/714912_1)
Source: by Steve83 (Steve, That dirty old truck)

A, B, C, D, E, F, G ,H, I, J, N, P, S Locations in an 83
Source: by Seabronc (Rosie, Fred W) at http://broncozone.com/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=11372

Repair & Color/ Gauge sizes; "... Fusible link wire is normal wire with special insulation designed to contain the heat, spark, and melted metal when the wire burns from excessive current draw. Fusible link wire is not rated in Amperes since its characteristics are less-obvious, but it is typically 4 gauges (AWG) smaller (higher number) than the circuit it protects. Although many vehicles now use MEGA or MAXI fuses where older vehicles used fusible link wire, replacing older fusible links with fuses is not recommended unless the rest of the wiring is upgraded to match the newer arrangement. Never replace a fuse with fusible link wire. In an emergency, smaller-gauge wire may be temporarily substituted for fusible link wire until an appropriate repair can be made; Orange - 22ga. - 0.35mm; Gray - 20ga. - 0.5mm;
Blue - - - 18ga. - 0.8mm; Black - 16ga. - 1.0mm;
Gray - 14ga. - 2.0mm; Blue - 12ga. - 3.0mm;
Orange - 10ga. - 5.0mm; Black - 8ga. - 8.0mm..."
by Steve83 http://www.supermotors.net/registry/media/830776

10-25-2012, 12:03 PM
yo, I lost this when Comcast froze during my reply

in the Wiring Diagram in 84 Bronco & F-Series (partial); "...Similar to 80-91 Bronco & F-Series..." check for power from Batty + post/terminal to Starter Relay to Ign Sw, etc.
Source: by Steve83 (Steve, That dirty old truck)
Ensure Starter Relay is mounted tightly to inner fender with no rust or grime

Fuse Block Diagram in a 85
Source: by Tim O (RED WAGON, redwagon) at FSB

a normal battery that is fully charged produces 12.6 volts, not just 12.0 V. (Remember, when measuring battery voltage, everything in the car should be off, or the battery should be disconnected.

Alternator Base Voltage, No-Load
voltage should be in the range of 14.1 to 14.7 v
Check negative battery cable to all grounds

10-25-2012, 01:19 PM

I will definitely check the fusible link to see if that is my issue. Do you know if I could go to an auto part store and get a new one?

I am hoping that this is the issue because like I said the battery, solenoid, regulator are all new now and the fuses look good.

10-25-2012, 03:26 PM
The starter relay (NOT solenoid) couldn't have just fried while the battery was DISconnected - you must have hooked something up wrong. Did you reverse the cables on the battery? Did you rearrange them on the relay? Click this, read the caption, & follow the links in it:

http://www.supermotors.net/getfile/809586/thumbnail/starterrelayterminals.jpg (http://www.supermotors.net/registry/media/809586)

Yes, you can replace a fusible link wire, and most decent parts stores sell them (stay OUT of the zone).

http://www.supermotors.net/getfile/830776/thumbnail/fusiblelinkrepair.jpg (http://www.supermotors.net/registry/media/830776)