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On 24 Jul 2003 at 9:44, Mike Wodkowski wrote: > on 7/19/03 3:13 PM, Jim Adney at jadney@vwtype3.org wrote: > > To work right the brain needs electrical power this means that it has to have > > both a 12V connection AND a good ground. If either of these is missing the > > brain won't work at all. To check either of these directly you have to pull > > the brain out and check for 12V on pin #18 and continuity to ground on pin > > #19. > While I know this isn't my problem, just wondering specifically how to hook > up my voltmeter to do this. Remove the brain and open it up. Remove the multiple pin connector and figure out which pins are 18 & 19. Get out your voltmeter and connect the black lead to a good ground on the car somewhere. Set your voltmeter to read DCV (on some range just above 12V.) Turn the key ON. Touch the red voltmeter lead to pin 18 on the wiring harness. Verify that there is something close to 12V there. Turn the key OFF. Set your voltmeter to read Ohms. Touch the red voltmeter lead to pin 19 on the wiring harness. Verify that you have something close to zero Ohms (less than ~2 Ohms is probably fine.) Now that everything is apart, this is a good time to check other resistances out thru the FI wiring harness to the various FI components. Most of these things are just a matter of measuring the resistance between 2 pins, or between a pin and ground, just to verify that the wiring harness actually makes a good connection to each FI part and that the internal resistance of the parts is approx correct. You can figure the pins and resistances out from the Bentley manual, but it is laborious. The Bosch FI testers do this, and a bit more. The main difference is that they just make it easy. Reassemble. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org