I am looking to install a VHF mobile radio in my '03. Does anybody have any experience or tips they wish to share about how to run the power cable to the radio from the battery or the fuse panel? The radio itself draws up around 10amps max at 13.8 volts. I have run power cables before in my other cars however I have no experience with my truck. Thanks for the help.



Keary

I ran a 4ga wire to a distribution block straight from the batt. You can mount it anywhere. Mine is on the top of the driver's side wheel well. You can pick them up at car audio stores. I then just tap into this each time I need power.

you do know its illegal to use a VHF on land right?

It's not illegal if he is licenced....right? Pehaps we should assume he is legally allowed to have the radio instead of assuming he is a criminal.

you do know its illegal to use a VHF on land right?

What are you talking about...?? there are many VHF services out there that he could be licensed for..

Ham, business band, rail, just to name a few...

Howard

Hi Keary,

Yeh, had the same problem in getting power to the 2m/440 Ham rig. I really don't like those fuse box taps. Kinda clunky in my mind.

What I've been doing for years is to use one of those Bosch 30 or 40 amp automotive relays to provide power for such devices (available at almost all automotive stores like NAPA, PEP Boys, AutoZone. I mount the relay on the firewall next to where the wires go to the wiper motor. One of those wiper motor leads is a switched (ignition) line that makes a very handy "trigger" for the relay. I think it's the yellow wire (I'll check if you want to go this route).

I used #10 wire with a large ring crimp-on connector and draw the 12v power feed from that junction box where the two batteries are connected together. A very handy place to pick up LOT S of 12v power. I run the #10 through the same hole that everyone drills to bring in their pyro leads/Juice Display wires through.

I then mounted a fuse block in the console to power the ham rig and CB.

Have fun,
George

Thank you for the constructive input. Perhaps I should have mentioned that the VHF radio in question is a 2 meter transceiver for which I am licensed to operate. All I need to know is where do I drill the hole at? I am not running any Juice,etc so I have no idea where to drill at.

Keary

Keary See my 2 responses to K3MP in this forum . Tis wil clear up all of your questions .
Daryl WB9DUC

Hi Keary,

Yeh, had the same problem in getting power to the 2m/440 Ham rig. I really don't like those fuse box taps. Kinda clunky in my mind.

What I've been doing for years is to use one of those Bosch 30 or 40 amp automotive relays to provide power for such devices (available at almost all automotive stores like NAPA, PEP Boys, AutoZone. I mount the relay on the firewall next to where the wires go to the wiper motor. One of those wiper motor leads is a switched (ignition) line that makes a very handy "trigger" for the relay. I think it's the yellow wire (I'll check if you want to go this route).

I used #10 wire with a large ring crimp-on connector and draw the 12v power feed from that junction box where the two batteries are connected together. A very handy place to pick up LOT S of 12v power. I run the #10 through the same hole that everyone drills to bring in their pyro leads/Juice Display wires through.

I then mounted a fuse block in the console to power the ham rig and CB.

Have fun,
George

What I am hearing is you can buy a relay where it turns the connection on to the batteries with a 12 volt starter signal? Where is that junction box where the batteries tie together?

THanks,

Drew

Unless you have some unusual factory options there are 3 unused circuits you can tap into inside the cab. They are available in the Relay Block I/P, also called the Mid Bussed Electrical Center (MBEC). This is the junction box under the dashboard to the left of the steering column that a trailer brake controller also plugs into.

After you remove the cover, locate connector C8, which is the upper-left position. There shouldn't be a plug in it. Pin D, the upper right pin, is hot in ACCY and RUN. It's fed through the SEO ACCY fuse, 10A, in the Left I/P fuse block. Pin A, lower left, is always hot. It's fed through the SEO B2 fuse, 30A, in the underhood fuse block. Pin E, middle right, is always hot. It is fed through the SEO B1 fuse, 15A, in the underhood fuse block, Pin F, lower right, is a ground. As far as I know, these are totally unused circuits. Why GM ships the trucks with the fuses inserted is beyond me when they're removing other features that most people care about. The other available pin in connector C8 is pin C, the upper left pin. It is hot in START and RUN, and fed by the 10A SEO IGN fuse in the underhood fuse block. This circuit also supplies power to the rear window defogger relay coil (not the defogger itself). I don't know anything about pin B. It's possibly not used.

You can use various modified connectors to hook onto these pins. The correct connector is a black 6-way Metri-Pack 280 series unsealed connector. They do not seem to be easily available. I saw a post mentioning that they were over $40 from the dealer but I haven't checked that out myself. The only other source I found was a distributor that sells them in quantities of 2,000. If you don't mind a little surgery for a compromise solution, you can pick up a brake controller harness at an RV store for about $15. If you get the one that plugs into a Prodigy brake controller (the most common harness version), the 4-way connector that you cut off and don't use contains 4 female spring connectors that fit pretty well on the Metri-Pack 280-series male pins.

The trailer connector is meant to go into position C7 of the MBEC, just to the right of the C8 connector I'm talking about. At first glance, it looks like you can just cut one keyway in the trailer connector and it will fit into C8, but it's not than simple. If you look closely you'll see that the C7 and C8 layouts are actually rotated 180 degrees from one-another. So on the trailer connector you need to cut off the locking tab, the outer-edge keys, plus one center key. It will then plug cleanly into the C8 position, upside-down. You can pull the blue locking tab on the trailer connector, then use a small screwdriver to pop out the individual connectors and rearrange them as you wish. A carpet knife works well for the surgery.

One other thing that's easy to access is the dimmed instrument lamp feed. There is a pin on connector C5 of the MBEC, also normally unused, that carries this. C5 is the 2nd-from-the-right connector position on the top row. The instrument lamp power is on pin F, the lower right pin. An alternate place to tap into this same line is the unused PTO connector. (I'm assuming here all of the trucks were built the same as mine). When used, the PTO switch replaces the cubby in the lower-right instrument panel. I think the airbag switch is there on extended-cab models. The connector is taped and hanging behind this cubby. You can get to it by removing the cubby, or by dropping the glove box door and reaching in a little to the left. It's an 8-way connector, smaller than used in the MBEC. The wires going to it are yellow, black, blue, brown(x2), green, brown/white, and grey. If you look at the face of the connector with the locator tabs up, the instrument lamp power is in the second-from-the-top position on the right hand side, which is pin C. It's the brown wire with the white tracer. I used a pin from a "snappable" header to plug into it, but any solid wire of the appropriate size will work.

Wayne... see this is why I participate... Very helpful... is there anything useing any of the power coming off that plug at all already. I want to calculate loads. I think I will be fine running off the 10A for all my yellow (12v ignition stuff) and that 30 amp will be fine for all my red wires I believe... I have an additional 2 runs of #5 wire for an inverter running to where I need power but for DVD players and screens this will work better I believe... What is the best way to get plugged into these? I am not in front of it so this may be a dumb question but is not the front side of this (MBEC) all fuses and then you can unclip and get to the back?

Drew

Drew,

The 3 circuits I mentioned, as far as I can tell, are totally unused. The 30A always-hot circuit is used to power the roof beacon. The other always-hot circuit powers the thermo-console and roof beacon switch. I didn't find what the switched circuit is used for. The MBEC contains no fuses. Just relays and connectors. Everything I talk about is accessed from the driver's footwell. The back side is connectors to the truck's wiring harnesses.

I added more information to the previous post to keep it all in one place.

Thanks... I was looking at the fuse panel... It has the fuses in there so I was thinking that was it and being thrown off by the fuse numbers... What is strange is have you looked in the fuse block there.... What is the red jumper wire for, it has a blade on each end inserted and linking 2 fuse blades?


Drew

Thanks... I was looking at the fuse panel... It has the fuses in there so I was thinking that was it and being thrown off by the fuse numbers... What is strange is have you looked in the fuse block there.... What is the red jumper wire for, it has a blade on each end inserted and linking 2 fuse blades?


Drew

I don't have this jumper in the '03. I assume you're talking about your '05, and the fuse block in the driver's end of the instrument panel. If you can give me specifics I'll try to look it up on the wiring diagram. Looks like something has changed.

No biggie it is just kind of wierd, what would be handy is to have a diagram of that MBEC panel all labled. I think I am looking at the same thing you have described and went and got some individual little thingies that will slide on those pins one at a time. I know I can find C8 Pin D... If I remember correctly there are 6 pins on one of those connectors 2 at a time side by side and there are 3 vertical sets. So Starting on the left it goes ABC up and DEF down on the right. This will really help. I should be operable in the morning...