Re: Sears meter
 

When I hook this Sears mutlimeter #82139 up to my car with the key on and the engine off I get a set reading of 30%, instead of 70%. Is it safe to say that it is reading backwards or do I have something hooked up wrong. Btw this is on my 89 300SEL.

Though I haven't used my new one yet nor read the manual in detail, in other posts here it has been said lead reversal is necessary.

Steve

From an article :

<<Mercedes has chosen the less common definition of "duty cycle" in this case. They are referring to the percentage of the entire pulse period during which the voltage is zero, not the time when it is near battery voltage (mine was +13.6 V when the battery was +14.0 V). In other words, if the pulse rests at ground for 7 milliseconds and then rises to +13.6 V for 3 ms, the duty cycle is considered to be 70% >>

Thanks for your quick responses.:)