Thread: Computer doesn't come on in ACC.

Originally Posted by Maheriano

Normally when you turn the key to ACC, the radio should come on. And then when you turn it to the next click, the fuel pump and all electrical comes on. Then another click and the car starts. But my computer only comes on when the car starts, yet I have the power running straight from the battery, and switched wire going to the switched wire of the wiring harness in the dash. It's the same switched wire I used to have the old deck running off and that worked in ACC. What's the difference? What am I doing wrong?

You probably use the "wrong" wire when you think it is right. Double check it.

It is the correct wire, there's only one switched wire in the harness.

put a test light on it

your m1-atx might not be switching on if the battery voltage is too low

10 minutes of probing with a multimeter is worth far more than pages and pages of guessing on a forum thread. If you have a carPC, I would hope you have a multimeter, as it's an indispensable tool; if you don't, go buy one. You should have no trouble getting one at any auto parts store, radio shack, etc for $10-15 or less. I've even seen the cheap made-in-china ones go for like $2 in the bargain bin at the auto parts store nearby, so there's no excuse to not own and use one. Then you can know for sure if the wire you are so certain is ACC, is actually ACC, and if the battery and ACC lines are at the proper voltage where they reach the M1-ATX, and then people can help you proceed from there if you don't find the problem immediately, instead of shooting blind.

I don't own a multimeter. If you've read my other threads, you'd know I don't really own anything.
But I am, however, open to suggestions so I will buy one and would appreciate very much if you can give me a 30 second crash course on using it........red probe to wire and black probe to ground and then look at the reading? Seems pretty simple. It is a 10 foot wire going from the M1 to the switched wire, through the harness, then to the battery so I guess the voltage could be too low. That's good advice, I'll try that. So I'd check the voltage at the end of the wire where it hits the M1 right? Do I have to unhook it from the M1 to do that? I have a real nice solder/heat shrink job done on it. Or I guess I could do it on the Ampie harness where it plugs into the case......yes, I will try that.

Yes, with the multimeter set to measure DC voltage it is really that simple. Since the cheaper ones aren't autoranging generally, just make sure you set it to the 20V range or higher (ie - measuring from 0-20 volts).

http://www.kpsec.freeuk.com/multimtr.htm seems like a good intro that you might want to check out.

As I said, multimeters are extremely versatile, you can measure voltage, current, resistance, continuity, etc. so it's definitely something you should get familiar with.

Originally Posted by Maheriano

It is a 10 foot wire going from the M1 to the switched wire, through the harness, then to the battery so I guess the voltage could be too low.

Here we go again,

WTF does that mean.

Your accessory wires come from the battery, through the "harness" to the switched wire?

Michael

A switched wire goes to the stereo harness in the dash. A wire goes from the switched wire on the computer to this switched wire in the harness. They join, the computer turns on with ignition. Not with ACC. I don't really get your question.

Originally Posted by Maheriano

A switched wire goes to the stereo harness in the dash. A wire goes from the switched wire on the computer to this switched wire in the harness. They join, the computer turns on with ignition. Not with ACC. I don't really get your question.

My question is because you state it comes fromt he battery, to the harness, to the acc of the PS. You never ID'd the "harness" you refered to. Now you state it is the stereo harness. That is information you should have posted the first time. Then, why do you state it comes from the battery. All electricity in the car comes from the battery (well, the alternator, but, whatever), so it is assumed. You ACC source has nothing to do with the battery per se. It's like saying, The power for my home Computer comes from the the wire, from the wall, and from the power station of the Canadien power authority. We know it comes from there.

Now, does your Stereo come on in the ACC position, or only while running?

Michael