Wirlybird

Do you really think the volt gauge would run off a relay?

If there was a relay, any idea where it may be located?  I am learning as I go on this truck!

I did find one thing that was a drain.  Someone had wired the A/C clutch directly to power so you connect the battery, it engages.  Clip - solved!

My current meter only does AC power draw so I can't test for any DC power draw.

1 hour ago, theakerstwo said:

Some trucks had the voltmeter working all time.  And that is ok because it will not discharge your battery.

Ahh, ok.  My friend though it used to go to zero when the truck shut off, but he isn't positive about it.

We are trying to track down a battery drain.

You can imagine the wiring nightmare in some areas on this truck!

33 minutes ago, Wirlybird said:

Ok, got a question.

 

I am redoing some wiring and I found that the volt gauge has 2 "grounds" going to it and 1 hot.

Both grounds appear to go into the harness.

Gauge works but is on all the time.

I think I figured it out.  Now that I can see the back of the gauge better it looks like one is a chassis ground and the others are really a 12v line in and out.

Ok, got a question.

I am redoing some wiring and I found that the volt gauge has 2 "grounds" going to it and 1 hot.

Both grounds appear to go into the harness.

Gauge works but is on all the time.

8 minutes ago, Steel Nose said:

As you can tell by my user name I love those steel nose RD's

I was thinking exactly that!

I failed to ask if I am posting in the correct group for this truck.

10 minutes ago, Steel Nose said:

Model is RD686S, And 7201 is the serial number

Thank you!

8 minutes ago, Steel Nose said:

That truck was built 01/07/1980 That was before they were using the 17 digit vin numbers. ENDT676 engine (285hp) TRXL107 transmission (6 speed)

44,000 camel back suspension CRDPC92/CRD93 Carriers 4:17 ratio FA617C front axle 

Hope this helps

That is great info, thank you!
Was there a model number/name?  Like Rd?

I changed it to the whole number.  Thank you.

Hi all,

New here and we have an older Mack we'd like to get some info on if possible.

I tried using the VIN decoders, but they ask for a 17 digit VIN and ours is only 10 digits.

VIN is RD686S7201

Thanks for any info and I am sure we'll be asking a bunch of questions!