20014x4

Good morning all.
I've got a couple of codes I need help with or some advise.
1st code is 0622 Alt field not switching properly. (is it time to replace the alt.?) gauge shows 14 volts.
2nd code is 1597 speed control sw. always low? Could they be related? or will an APPS reset help?
3rd code is 0128 I cannot fint that one in the list.
I've got 175000 mi on the truck.
Thanks for the help

John Faughn

I found 0128 = cooling system error / thermostat perf.
Have the batteries load tested , check all connections , test charging system , clear codes [ after writing down all info ] .
I've seen a lot of errors with voltage problems .
Then if codes come back look at them again .

20014x4

Thanks for the advice. gonna check everything today. I noticed this morning that my engine temp was running kind of cool. so I think a new thermostat is in my near future. thanks again Ray.

vzdude

The alt not switching code is typically from the batteries being weak. The grid heaters and starters are bringing the voltage down so low that the alt is basically staying charging too long trying to keep up. Computer sees that as a problem and sets a code. Get the batteries load tested and I'll bet that is your problem for that code. Agree on the t-stat causing the other code too! As for the speed control switch, check the brake switch, or the wires in the colunm. Could be either one, or the switch itself.