Power for Gauge question...

[scootergmc]

Please keep in mind I am an electronics knucklehead. I can run wires, hook things up, troubleshoot problems (like why won't my trailer lights work, etc), but I don't really understand principles of how it all works... so here goes...



I just got my four Isspros (fuel press, transmission, boost, and egt). My concern comes with running them all to the same power source. Will I be OK? I've read about people installing fuses and relays... is that required? What parts do I need if it is? I know about connecting 12v to the cig lighter but where to I run it to on the gauge? I run power to the lamp terminals on each gauge?



I'm looking at my temp gauge and notice it does not come with the power wires. I need to run power wires from the back of the module box to the dimmer? Is that correct?







Sorry if I'm an electrics idiot. I've read most of the gauge installs (I think) and I can't find one that just deals specifically with wiring. Thanks.

 

[JVolpe]

Well you seem to have the basics down. Did you get the install instructions and all needed wiring with the gauges?



What are the guage model numbers? You can go to the Isspro website ( ISSPRO Installation Instructions ) and look at each gauge install instructions if you do not have them.



You can run all of the power from the cigarette lighter and tap the dash dimmer wire going into the light switch for the gauge lights. Just make sure that you have good ground wire to each gauge.

 

[RJWEST]

the fuse ' dimmer' is same as dash light voltage,
get a ' add a fuse' " piggy back"" and wire it to the gages...
easier and cleaner install


the piggy back fuse replaces the dimmer fuse and provides another fused outlet... .

 

[rbattelle]

For the gauge backlighting, you need power from a source that is already powering a dashboard lighting circuit, so the gauges will dim when you dim the dash lights.

The cigarette lighter power source is a constant 12v, so you don't want to hook that to your gauge lights - they won't dim.

I think most people tap one of the wires in the headlight switch circuit. This thread discusses it.

Some gauges require no power other than the backlight. Your temperature gauge is probably one of that type. Other gauges also require a 12v power source - usually gauges with a signal amplifier of some sort.

The instructions from Isspro should clearly indicate what wires each gauge requires.

It's hard to describe wiring to people... much easier to show them what to do.

Ryan

 

[LRutigliano]

Scootergmc,



If you go to DieselManor - Taking the Mystery out of Diesel Performance™, they have intructions and excellent pictures of what you need to do. Go the gauge install instructions on their website.



Hope this helps,

Louis

 

[JDecanter]

I put my gauge pod and gauges on a table. I then put the gauge loosely in the pod, ran all the black wires into a single black and all the red into a single red. (your colors may be different) But when you get all the hot wires into one and all the ground wires into one you will only be hooking up two wires: one to a ground and one to a hot. I found that I did not need mine dimmed, so I simply tapped the pink wire with yellow tracer in the big bundle near the parking brake.

 

[scootergmc]

Thanks for the replies. I've made it as far as installing the sensor for the transmission temp gauge. That's because all I did today was install the new pan.



I do have the instructions for each gauge. I need to have six power sources, one for each light, and then the two addl. for the boxes on the temp and pyro gauges.



Here's what I understand. The light connects to the back of the gauge. I should wire all four together and connect that lead wire to the dimmer wire in the headlight switch. Now should I put an inline fuse in that one wire? I've read some people do it, and I've read others say it's not necessary. If I put in an inline fuse, what amp fuse should I use?



Also, the power for the boxes for the pyro and temp gauge get wired to the cigarette lighter (or any other key-on hot) correct? I can also connect the two and run one wire... Do I need an inline fuse here? It's also interesting the box for the temp gauge does not have the power leads like the pyro box... .



I'm a little stumped as to hooking up the fuel pressure gauge isolator. Do I really need to use the coolant? Can I get away with just the air... . I'll search the forums a little more there...

 

[rbattelle]

Here's what I understand. The light connects to the back of the gauge. I should wire all four together and connect that lead wire to the dimmer wire in the headlight switch. Now should I put an inline fuse in that one wire? I've read some people do it, and I've read others say it's not necessary. If I put in an inline fuse, what amp fuse should I use?

Technically, yes you should put a fuse in there somewhere. The size of the fuse is dictated by the ampacity of the wiring you're using. You want a fuse that is smaller than the ampacity of your wire. Here's a link to an ampacity chart. For example, 12ga. wire in open-air has an ampacity of 23 amp. So you'd want a 20 amp or lower fuse to protect that wire. [Ampacity is actually also a function of insulation and whether the wire is in an enclosure or not. But the chart I linked to should be safe to use for your wire, as it's ampacity values are actually for wires running in an enclosure].

Bottom line: unless your wire gauge is really small (smaller than 18ga. ), I'd run a 10A fuse.

Also, the power for the boxes for the pyro and temp gauge get wired to the cigarette lighter (or any other key-on hot) correct?

Correct.

I can also connect the two and run one wire...

This should work fine.

Do I need an inline fuse here?

I would use one. Follow the sizing advice I gave earlier.

It's also interesting the box for the temp gauge does not have the power leads like the pyro box... .

Probably because the temp gauge is an RTD (Resistance Temperature Device), which works differently from a thermocouple. No amplification is required for an RTD, since it works by measuring resistance rather than voltage.

Do I really need to use the coolant? Can I get away with just the air... . I'll search the forums a little more there...

I wouldn't use air. You want to use an incompressible substance - like coolant or water. Otherwise your readings may be off.

All those inline fuses can be a pain. That's why some of us run auxiliary fuseblocks instead (like the Painless one Geno's sells). Much neater install and your electrical items are independent of the vehicle system (other than the battery).

Ryan

 

[scootergmc]

Thanks. Yeah, I'm starting to like the idea of the painless or similar box. Where does the painless pick up the dimmer? I would still have to run the gauge wires to the dimmer, correct?



I'm also not too sold on the mechanical fuel gauge though. Seems like the electric one would work just fine (with a lot less mess) and I wish I would've checked it out a little better before purchasing. Live and learn.

 

[rbattelle]

Where does the painless pick up the dimmer? I would still have to run the gauge wires to the dimmer, correct?

Right, the painless has nothing to do with the dimmer. The dimmer wire would still be run directly from an instrument panel lights circuit to your new gauges. No fuses needed.

I'm also not too sold on the mechanical fuel gauge though. Seems like the electric one would work just fine (with a lot less mess)

Personally I don't like the mechanical gauges. A lot of people swear by them, although I suspect it's more out of a fear of electricity than anything else. I use all-electric gauges (except my boost gauge).



Ryan