Volt meter ?
 

Bought a volt meter to start checking my engine's idle problems but must be doing something wrong. I am trying to check my throttle switch according to Bentley, but am getting a (-) or (0) reading instead of the 5 volts expected. The instructions that came with the volt meter are very basic so I am not sure how the voltmeter should be setup. What am I doing wrong? Should the car be running in order to get current? Help.

Michael
87 Targa

Michael,
Set the voltmeter on the dc ( direct current) scale. The other scale is ac (alternating current) the kind you have in the wiring at home, the other is resistance.
Next, select the range, a voltage range that is larger than 12, the voltage in cars.
Connect the ends of the 2 meter leads to the connections you are interested in and then go switch the switch and see if you get the 5 volts in one position and 0 in the other.
Next, disconnect the idle switch, alogside the full load connector and connect the leads across the wires coming from the switch. This time, use the resistance scale on the meter and you should see the resistance swing from 0 to max each time you open and close the idle switch.
Um, ah, is there any chance you have connected to the idle switch instead of the full load switch.
Ned Monaghan

Ned-

Thanks for the help. Do I need to test the throttle and idle plugs for volt and resistance both? Lastly, how do I open and close the idle switch?

Michael
87 Targa

Michael,
The idle switch is in front of the throttle lever and can be seen with a mirror. It is normally closed and opens when the throttle is closed. You can see it and the rod that opens it with a mirror.
When the throttle is closed this switch opens, and that is what you want to check. Use the resistance scale in the voltmeter. There is no voltage across this switch.
In the event that it does not open at idle you must adjust the position of the switch so that the lever opens it at idle.
This is a really difficult job on account of the inaccessibiity of the switch mounting screws ( phillips). I finally switched them for hex head screws that were easier to tighten.
Read Bently before doing this job.
Ned Monaghan