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Beefing up the fuse panel...

nutt7

nutt7

1/2 ton status
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Ahwatukee, AZ -> JBLM, WA
I (and others) have noticed a significant voltage drop from the battery to the cab accessories. I measured anywhere from 1-2 volts, depending on what is loading the system. I think it is because the 12 gauge wire that takes care of most power isn't up to the task. Most of the voltage drop happens after the ignition switch, where the 12v switched wire splits up and runs to many circuits.

I want to run an additional 12v wire into the cab to the panel and another one in conjunction with a relay to support the 12v switched circuits (so it doesn't have to pass through the ignition switch). I pulled the fuse panel and noticed that most of the "input" sides of the panel have additional unused crimp points on the busses to attach more wires. I plan to tap my new supplies to these terminals so the accessories will have more current available (I might also do this for the accessory plugs above the fuses since some are unused/unsupplied).

The open terminals have the bare wire crimp point and the insulation crimp point. My only concern is that I can only crimp the bare wire on the insulation part, since the other ones are too deep and already closed. Do you think there will be an issue crimping the wires there? It doesn't look flimsy, nor is it sticking out so far as to short out. What do you think? am I overlooking anything?
 
I figured out how to remove the pins from the back of the fuse panel so I will be able to get a proper crimp on wire and insulation. Those metal busses are kinda flimsy. After I do this I will post back any noticeable results.
 
tagged.

I have had power problems too. I will be adding more grounds when I get my engine and trans back in. I just had my fuse panel loose to trace the wires and check on the integrity of the connections. I may have to follow your lead if things don't improve after cleaning up the wiring and grounds.
 
Honestly, I think instead of wasting time on the fuse panels (which I agree, seem to show significant voltage drop) it is a better idea to get an underhood fuse/relay center off of a more modern vehicle, and use that to distribute power.

As mentioned, use the relays for the ignition sources, and run things from there.

At least in regards to adding electrical components, the fuse/relay centers offer a lot of functionality vs. taxing the limited (and unfused) accessory terminals.
 
dyeager535 said:
Honestly, I think instead of wasting time on the fuse panels (which I agree, seem to show significant voltage drop) it is a better idea to get an underhood fuse/relay center off of a more modern vehicle, and use that to distribute power.

As mentioned, use the relays for the ignition sources, and run things from there.

At least in regards to adding electrical components, the fuse/relay centers offer a lot of functionality vs. taxing the limited (and unfused) accessory terminals.
Click to expand...

That is basically what I am doing. I built a sheet metal box to sit on my inner fender and house fuse blocks and relays for my extra accessories and aftermarket gauges. I have extra lights, air bag compressor, rancho shock compressor, stereo, electric brakes, power windows, power locks, gearvendors overdrive, power for trailer plugs, etc. All of these items will connect to aftermarket fuse blocks rather than using power from the original fuse panel. I already had them wired up, but with the engine out, I wanted to make something a little cleaner and more weather proof.

I looked for waterproof fuse blocks, but many have exposed connectors for the wires, which is pointless under the hood. The aftermarket blocks can get very expensive. I thought about a junkyard plastic fuse block, but I needed numerous circuits from bat1 bat2 and accessories switched fuse blocks. I didn't need the circuits for signals and all the stock parts. It also would have been a square box sitting on a curved fender and may have looked out of place.

I built a sheet metal box that fits the contour of the inner fender and it will house relays with sockets and 4 of the cheap 6 circuit fuse blocks. I will use some electrical grease on the contacts to help keep water out and the box will be fairly weather tight. The fuse blocks cost around 10 bucks each at the auto store and are very similar to the expensive painless fuse blocks that are not any more weather tight.

The old:
IMG_20130625_154714_873.jpg


The new (still in progress):
IMG_20130817_143636_705.jpg


IMG_20130817_143735_685.jpg


I was going to go out and put the inner fender and box in the engine bay and start to get my wiring cleaned up, but it is 102 degrees in the shade. The parts are sprayed black with satin clear coat. There are more details in my build thread.

If I have to, I will move my headlights, ac blower, or other components to fuses in the new blocks. I used 4 gauge wiring for the alternator and batteries and up to all the fuse blocks. My original fuse panel connects to the main lugs on the new fuse blocks and no longer runs to the starter, thus eliminating a place for the wires to get hot.
 
Dyeager: I did do that (see above), but I want to alleviate a little more stress on the old wires going inside. Besides, I have too many extra wire and relays laying around!
 
nutt7 said:
Fans,-rad,-fuse-box,-parallel-flow-condenser,-tranny-filter-cooler-pics...and-blood
http://coloradok5.com/forums/showthread.php?t=299422

Click above to see what I did so far. Not too fancy, but it works.
Click to expand...

That fuse block looks good in there. Maybe I should have searched the junk yard. My box will also house the th400 kick down switch and the gear shift indicator switches that I have sitting on the inner fender, so it is a plus there. I just hope it doesn't turn out looking like a stupid shoe box mounted in the engine bay. At least it fits the contour of the fender and I can always remove it with a few screws and start over if I really don't like it. At this point, I am just ready to get it running again so I can drive it.

GM picked a really bad spot for the original fuse panel in these trucks, at least for those of us who are crazy enough to add every creature feature that the new trucks have, and then some. My neck screams every time I have to mess with the fuse block. On top of the mounting location, the printing isn't clear on mine and the fuses don't seem to be in nice rows like the new ones. Well, at least they got better with the newer trucks.
 
nutt7 said:
Dyeager: I did do that (see above), but I want to alleviate a little more stress on the old wires going inside. Besides, I have too many extra wire and relays laying around!
Click to expand...

I can understand having stuff lying around and wanting to use it. :)

What is "high draw" in the cab that is really dependent on minimal voltage drop? I'm racking my brain trying to come up with something, and other than the voltmeter, I can't think of anything that isn't just an on/off proposition with low draw. Maybe the heater motor if non-AC?
 
Power windows and locks (sometimes locks don't fully lock), rear blower fan, front blower fan on lower settings (high setting is supplied by distribution block), a/c clutch (not sure of draw on that). The blower fans and a/c kill it the most. Makes my slow windows SLOOOOOWWWWer. I would like to have a cb radio eventually, I like to run an inverter once in a while too.
 
Little bit of a hijack here, but may be relevant to the voltage drop.

Voltmeter in my truck reads low. Alternator checks out, everything is good as far as I can tell. When I turn on the headlights or wipers or an electric fan turns on, the volt meter drops like a stone. I'm thinking its something in the firewall plug that is causing it.

I'll follow this thread and see where it goes. I still can't decide if I want to rewire the whole thing or just tie in to the existing harness when I do my dash work.
 
I checked mine with a voltmeter and it tests similarly on either side of the bulk connector. The more the interior gets loaded, the more it drops.
 
Forgot the windows and door locks. Agree, particularly with windows, the draw is probably fairly significant. Lubing the window components (and replacing anything in them that is worn/binding) may help just as much if not more than electrical re-work, if you haven't done that.

I've noticed one of my power door locks randomly works, but I've had a similar problem before, and the problem was from the door lock solenoid not getting a very good ground through the bolts that held it to the door. Similar to the headlight switch, they rely on the mounting to the sheet metal for the ground, but the sheetmetal is painted, and thus not a particularly good ground without scuffing the metal up. Just a thought there.

I suspect much of the decrease in voltage into the cab is based on the charge wire on the alternator. I could be wrong, but that seems to be a consistent issue....with two feed wires to the fuse panel, but only one of approximately similar diameter of one of those wires from the alternator, I would expect there to be some loss there.

When I re-did my cluster with LED's, I measured voltage at the cluster connector and compared with the voltmeter on the cluster, and they were very close. But even though I've got a 100A CS130 alternator (far more than I need, since I have very little more than stock electrical load under normal conditions), if I turn the heater on high, and/or use the tailgate window, I can watch the voltmeter drop and then recover when I stop using them. It's not below 13V or so, but its noticeable.

I have not spent the time to REALLY delve into the charging "issue", but even in your case I'd spend the time with a voltmeter between the alternator, battery, and fuse panel with varying loads before doing anything else. Way back when, I noticed in-cab voltage was easily at least a volt less than what I was seeing at the alternator.
 
I remember that thread. :)

So did you ever get the low voltage output at idle solved? Did you ever measure the output of the alternator under the various loads? (if you did, I missed it, sorry) Realistically, the only one that needs to be considered is the output of the alternator under it's absolute maximum load, at idle.

I do not trust parts store bench testing, ever. The variables that exist in the vehicle, do not exist on the bench, plus, do you know the machine and operator are good? Normally bench testing is probably ok, but IMO I want to see what it's doing on the vehicle.

As for your ALDL readings, I'm sure that is fuse panel voltage, but no idea if it's constant battery voltage, or the switched ignition feed.
 
I get good output at idle fully loaded. Like 13.8, 13.9. I get a couple tenths drop to the distribution point on the firewall.
 
I would have suspected the largest drop to be between the alternator and junction block. Odd.

So you see more drop from the junction block to vehicle side of the fuse panel than from alt to junction block? Or is it just cumulative?

Should be able to check resistance through the firewall connector from the junction block (and through the fusible links first) to see where the most loss is.
 
Interesting...
I swapped a CS144 140 amp on my '89 and I'm getting 14.61 at the battery idling and I get 14.49 at the fuse box inside and 14.49 at the firewall. Drops down to 14.3 with everything on but numbers remain constant.
Keep in mind they heat up fast and volts drop off just as fast. When mine gets hot it drops down to 14.3 unloaded.
I'll have to read your thread and see how you got it wired up. Are you using the "S" terminal?
 
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