dek1581 Posted May 29, 2015 Share Posted May 29, 2015 I have seen posts in the past re: changing from the old positive ground setup to the more modern negative ground setup. does anyone know when Mack started making rigs (particularly fire trucks) with the newer arrangement? also, I would assume the change is more than just reversing wires on the batteries. there was a schematic posted once but I can't remember. I should have printed it. Quote Link to comment https://www.bigmacktrucks.com/topic/40238-negative-vs-positive-ground/ Share on other sites More sharing options...
mrsmackpaul Posted May 29, 2015 Share Posted May 29, 2015 theres not a lot more to change the regulator has to be fiddled with any radios or electronic equipment and the rest lights starter motor ect should all be pretty good I thinkPaul Quote Link to comment https://www.bigmacktrucks.com/topic/40238-negative-vs-positive-ground/#findComment-291652 Share on other sites More sharing options...
ws721 Posted May 29, 2015 Share Posted May 29, 2015 Theres a little more to it. Your Amp meter will have to be delt with, the heater motor wires need to be reversed, fuel gage wont work, radios will not take the change. I have in the past swapped the wires on Amp meter and heater motor and lucked out. Fuel gage? Did Mack ever make a fuel gage that worked anyway? 1 Quote Remember if it's got a hood it's no good! Link to comment https://www.bigmacktrucks.com/topic/40238-negative-vs-positive-ground/#findComment-291655 Share on other sites More sharing options...
j_martell Posted May 29, 2015 Share Posted May 29, 2015 <SNIP> Fuel gage? Did Mack ever make a fuel gage that worked anyway?The pig farmer I worked for had a 02 Granite with a perfectly functioning fuel gauge. Showed the amount of air in the tank. Ask me how I found that out. Luckily I was at the top of the hill when it "went to sleep", pumps where at the bottom Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/40238-negative-vs-positive-ground/#findComment-291663 Share on other sites More sharing options...
szafram Posted June 1, 2015 Share Posted June 1, 2015 (edited) I believe Mack switched from positive to negative ground in 1971 in fire trucks. (I had a 1970 CF that was delivered in December of 69 that was one of the last time come off the line as positive) I have also attached wiring diagrams from that truck from the original manual. Hopefully they help you out! Edited June 1, 2015 by IndianaFireman Quote Link to comment https://www.bigmacktrucks.com/topic/40238-negative-vs-positive-ground/#findComment-291915 Share on other sites More sharing options...
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