Check engine light on

[arlojanis]

On a new Chevy diesel pickup truck, if a device is connected to a fuse in the dash fuse box and the check engine light comes on, will the light go off when the wire is disconnected, or will the computer need to be reset? Can it be reset with a small code reader? What about other makes and models of trucks?

[tvsjr]

Depends on the code set. Just disconnect the battery (batteries if it's a diesel... remember they're in parallel - don't short one) and let it sit for 10 minutes or so. The computer will reset and dump all codes.

[kb0nly]

An OBDII code reader with erase function can clear it in a matter of moments, that's what i use. Cost me $68 from Wal-Mart, plug it in, turn on the key, let it read, and erase any codes one at a time with a push of the button.

I thought it was worth the investment to have it, especially since all the cars/trucks out there that i deal with are new enough to be OBDII now.

[kg4ere]

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[kb0nly]

Some vehicle computers are more sensitive than others. When i recently had an alternator problem, due to the sense wire connection to the battery being bad, the voltage was low and the traction/abs control computer was going wacky because of it.

I tend to ALWAYS use the car stereo circuit to run a relay to provide power to added equipment. It's quick and easy and you don't have to worry about much doing it this way.

The added benefit is the car stereo circuit is on and off with the key, and also off while cranking the engine over to protect the added equipment from damage.

You can get handy Tap-A-Fuse's from places like Waytek Wire. With these all you have to do is unplug say the stereo fuse, make sure if yours has an antitheft feature you know the password or disable it, plug in the tapafuse and then put the original fuse back in along with a second fuse that provides power to a pigtail lead coming off of it for your added circuit. Really fast and easy and safe, and the added benefit is that you don't have to cut, crimp, or butcher up the vehicles stock wiring making it 100% reversible.

[KitN1MCC]

i would not connect anything to Fuse box on the GM Vehicle due the very complex wireing

there are some better take off locations

[kb0nly]

Name one??

Taking off an existing fuse location is far better than hacking into stuff.

[kj7xe]

For years I've been using the 'add-a-fuse' holders (Tessco sells em) in the fuse panels of vehicles, and yes - finding the appropriate fuse to tap into to drive a relay can be a little tricky if you aren't sure how the particular circuit you chose to tap into actually behaves.

For a while I exclusively used the car stereo's 'ignition sense' wire, but when changing jobs I was told that for time/money-saving purposes not to 'hack into any wires and just tap into one of the fuses in the fuse panel'. Nowadays that's easier said than done. While in prior years you could just look for the 'radio' fuse and be good, it doesn't really work that way anymore. However that doesn't mean that there are no fused circuits that turn on and say on when the key is switched on or on ACC. They're in there, you just have to find them, look in the service manual, or ask someone that may already know. It just seems anymore that it would save time to not worry about choosing the wrong fuse circuit and just come off the car stereo's ignition sense wire. Then you don't have to hack up the fuse panel cover (if we're talking about Fords)...

[n1pfc]

I always run main power to the battery or when there's an under hood fuse block, the battery side of the maxi fuse. Helps cut down on possible corrosion.

Ignition sense runs are done with a pigtail fuse of the same rating to the fuse block. Tessco sells these as well. If you use these they dont mess up your fuse block. I've seen quite a few newer vehicles have messed up fuse blocks because of those brass tab power taps. They dont make them like they used to that's for sure.

Quick place to look for power that turns off when the truck is cranked is the fuse that runs the 4x4. I use that all the time on the GMC Envoys and various other chevys.

Kurt

[kb0nly]

I don't recommend those cheesy brass power taps either, use the fully contained and insulated fuse taps. Some call them tapafuse, the brand Waytek carries are called TAPA Circuit's, then you don't have to worry about messing up your fuse panel.

However, like i said, don't use this tap to run the equipment directly, use it to energize a relay that is supplied from the battery.


ATO:

http://order.waytekwire.com/IMAGES/M37/ ... 18_062.PDF

Mini:

http://order.waytekwire.com/IMAGES/M37/ ... 18_065.PDF

I also like to use their resettable breakers that directly replace a standard auto blade type fuse where possible, makes it more convenient than finding a replacement fuse late at night, etc.. Another nice option is the fuses that light to indicate a fault, fast and easy troubleshooting of fuse related problems in a out of the way fuse panel, or at night.