What the heck is this?

[calmyron]

Okay, I have a 1990 Laser RS Turbo that has been giving me fits. First it was an alarm system that was keeping it from running and a vacuum sensor on the air cleaner cannister. However, the latest problem is the battery has been draining without anything on. Fortunately, I've found the item that is draining my battery. As soon as I unplug it, the drain goes away completely. As soon as I replug it, it drains my battery in a matter of 30 minutes and it buzzes.

The problem is I can't find this bloody item anywhere in any repair manual. I can't find it on any explosions of the Throttle Body Carburator or Intake System anywhere. It's clearly bolted to the bottom of the carburator. It's just below the TSP (the black item in the picture) and has a couple of wires coming out of it to the connector on the backside of the carburator.

I've included the picture below. If anyone can tell me what the heck it is, then maybe, just maybe, I can get this Laser back on it's feet.

 

[boosting_laser]

It's the ISC motor or Idle Speed Control motor.

 

[92redman]

With the key off and battery hooked up, unplug it. Take your volt meter and measure all of the pins and please list your results.

 

[calmyron]

Okay, I did what you asked. Without knowing if you wanted voltage or not, I just assumed you wanted voltage and went from there.

I attached the negative lead to the negative pole of the battery, but I'm presenting all information as positive. If you need to know if it was negative or positive, I'll go back and do that, but here's what I have now.

 

[92redman]

How long was the key off for when you took those readings?

 

[calmyron]

Mmm... I'd say at least 72 hours. Probably more like a six days.

 

[92redman]

Can you pull off the tps connector and do the same thing with the voltage readings?

 

[Travi2506]

http://dmtalon.v8eaters.com/ISC.html tells you all about testing the ISC...

 

[92redman]

^^don't worry about that right now, no matter how screwed up the ISC may be, there shouldn't be any power going through it with the key off. If your voltage readings are correct, you have enough parasitic draw to cuase the battery to go dead over a couple of days possibly. We need to figure out why it has voltage now.

 

[92redman]

Before we go any farther, maybe we should verifiy that that connector is our drain and how much it is. Do you have capability to read current with your meter, and do you know how to use it so you don't blow a fuse?

 

[calmyron]

It's late and my flashlight assistant has gone to bed. I'll test it tomorrow after I get back from work.

 

[Travi2506]

Sorry Man, just tryin to help... but i'm a newbie so what did you expect?

 

[calmyron]

I'm pretty sure my multimeter can, but I'm not up on it. My father would know, him being a civil engineer and all, but he's in your neck of the woods. I'll call him and see if he can direct me over the phone on doing that.

 

[92redman]

The way I like to check for the parasitic draws is to take a jumper wire(not hooked to your meter at all), disconnect the ground side of the batter and take the jumper wire and connect it from the ground post on the battery to the ground terminal that was attached to it. What this will do is complete the circuit again and prevent your meter from getting a spike of energy when you hook it into the circuit.

With that jumper wire connected(making sure no lights or anything is on), take your meter with it in the high current mode and hook it the same way the jumper wire is(if you have a DVOM polarity doesn't matter, if you have an oldschool analog you should hook negative lead to the battery post and positive lead to the terminal to prevent damage).

Now when you safely have your meter in the circuit you remove the jumper wire and you should get a reading that represents the total current that all devices in your car are using(you open a door or cause any lights to come on at this point, you might as well go get another fuse). You should have a pretty low number, like under 20mV. Then you can plug your connector in and see if it changes(or unplug it if it was already plugged in at this point).

 

[92redman]

Here's a quick simple drawing of what I was describing, hopefully it will make sense. Basically what we need to know is the current with and without the isc connector plugged in.

 

[calmyron]

Sorry for the long delay. I work for myself and have to make time to work on this.

This is what I've found when I tried your current check. With the TSP unplugged, I attempted to put a jumper wire on the negative post to the ground clamp after removing the clamp from the post. While holding it, it started to get warm, so I removed the jumper and decided to test it without it.

My multimeter was showing over 12 volts.

Now, the multimeter I have has five settings. VDCV, VACV, K?, ->|- and Continuity. I used VDCV on this test.

 

[92redman]

You are going to got 12 volts, if you test like that. We wanted to test current, not volts. If you hooked it up like that, your jumper wire should not be getting warm if there is less than an amp of current flowing(if everything is right there should be only a few milliamperes flowing).

The sole purpose of the jumper wire is make sure any modules or devices that power up when the battery is connected can time out and shut down before you hook up your meter. This prevents a spike when you first hook your meter in the circuit.

It doesn't look like your meter has a built in ammeter and will not help for this test.
If you are not sure or are not comfortable using an ammeter, maybe you should have somebody else do it for you or at least watch over you shoulder to make sure you are doing it correctly.