30-0-30 ammeter. On Wed, 01 Nov 2006 22:33:54 -0600, Jim Cathey <[EMAIL PROTECTED]> wrote:
>> Got my 2 new GPs today so tomorow I'll try to find out what the >> problem is. >> To refresh memory - I have new GPs and new GP relay - preglow light >> goes out >> within 1 sec. of turning the key) > > That sounds like a problem internal to the GP relay. These things are > likely NOS, not new-new, and the timing capacitor could have aged to > death before you ever got it. > >> I got my DMM out and set it to >> Resistance - using a new GP I touched the threads at the top and the >> threads >> that contact the cylinder head - got a reading of .3 - then I crossed >> the >> leads and the reading was .0 - is it OK that my DMM doesn't have a >> reading >> greater than .0? > > Yes, you just cross the leads to find out what its idea of zero is, and > then subtract that from your reading. > >> How do I tell if my DMM will measure current in the range you >> mentioned -- > > Was it exceedingly expensive? Then maybe. It's usually clearly written > on the face somewhere, if it does current at all. > >> I'm thinking I need at least a 30A max? But I think my DMM is good for >> 0A's - it's from Radio Shack -- > > Most DMM's have a 10A current scale, if they have anything at all. > To measure more requires a shunt, rarely seen these days, or a > relatively expensive clamp-on DC ammeter probe. Even my $300 Fluke > only goes to 10A without the 400A external probe (another $200 IIRC). > Attempts to measure more than 10A results in blowing its internal > fuse, an item that costs more than an entire DMM from Harbor Freight. > > An old-fashioned charging gauge from the auto parts store could work, > those are usually 60A over a half-scale, so are a bit too crude to get > a good measurement off of. It would have detected my one bad one that > had 2x normal current, however. > > -- Jim > -- Luther KB5QHU Alma, Ark '87 300SDL (270,491 mi) head case? '83 300SD (241 kmi) '82 300CD (162 kmi) '82 300D (74 kmi) needs MAJOR engine work '85 300D (280,176) parts car
