Usage:
Machines Using 24 Volt Radios
Reference: Service Magazine, January 17, 1994, Page 15; "List Of Entertainment Radios For Earthmoving And Agriculture Equipment".
A problem may occur where the radio has a functional AM band but is nonfunctional on the FM band. If this problem occurs, especially on new installations, check the voltage at the harness for the radio. For a 24 volt radio the voltage must be approximately 24 volts. The AM band of the 24 volt radios will operate with a minimum of 12 volts applied to the radio; however, the FM band will not. This can make it appear that the FM band of the radio is nonfunctional when the radio really does not have a problem.
To check "Fixed Mount Radios":
NOTE: The disconnect switch must be on for the following checks.
1. The machine harness connector for the radio should have approximately 24 volts between terminals 3 and 4 of the harness connector (terminal 3 is ground) with the key start switch turned on. There should be 0 volts between terminals 3 and 4 with the key start switch turned off. There should be approximately 24 volts between terminals 3 and 5 of the harness connector for the radio with the key start switch turned on or off.
2. With the key start switch turned on and if either of the above voltages are not correct (particularly if they are in the range of 12 to 14 volts), then determine if a 24 volt to 12 volt converter for an entertainment radio has been installed on the machine. If it has been installed then the converter should be disconnected if it is not used for any other 12 volt device. If it cannot be disconnected, then a 12 volt radio should be installed.
To check "Quick Disconnect" (Anti-Theft, Removable) Radios:
NOTE: The disconnect switch must be on for the following checks.
1. The machine harness connector for the radio should have approximately 24 volts between terminals 3 and 4 of the harness connector (terminal 3 is ground) with the key start switch turned on. There should be 0 volts between terminals 3 and 4 with the key start switch turned off. It does not make any difference what voltage is between terminals 3 and 5 with the key start switch turned on or off because the radio does not have a wire connection to terminal 5; the quick disconnect radios have an internal battery to maintain station preset memories and do not need an external memory power input.
2. If the voltage between terminals 3 and 4 is not correct, then refer to the electrical system schematic for the machine and troubleshoot accordingly. Chart A lists the above voltage checks with proper results. Chart B lists 24 volt radio and radio kits by part number and description.
