Wiring Diagram

Chapter 7 Best Practices: Installation & Troubleshooting
In this section are Motorola Solutions recommended vehicle installation practices that can address or
prevent many issues, including:
• Radio circuit damage due to over voltage condition
• Radio/Accessories "lock up"
• Radio/Accessories change state/lock-up when radio PTT is depressed
• Radio powers up in the FL 01/90 state (general communication error code)
• Radio intermittently resets
• Radio loses secure key
• Transmit audio distortion on motorcycle radio when engine is running for mid power radios
• Keypad buttons become inoperative for motorcycle radios when engine is running for mid power
radios
• Alternator whine present when transmitting with engine running
• Radio/Accessories turn themselves on/off
7.1 Check Wiring of Ignition and Radio Ignition Sensing
• If it is required to turn the radio on and off through the ignition sense switch, in addition to the
control head on/off switch, connect the ignition sense lead to the accessory terminal from the
ignition switch (usually in the vehicle fuse panel under accessory or radio).
NOTE: Motorola Solutions recommends protecting or isolating the radio ignition sense input from voltage
spikes in excess of +/- 40 VDC. Such spikes can be hundreds of volts in amplitude and are
common in larger vehicles (utility trucks, buses and others), especially when the source is
common to a solenoid coil. A triggerable oscilloscope is required to determine the existence of
such spikes as most voltmeters cannot measure in short duration (< 1 msec). If the condition of
the intended ignition sense source is unknown, Motorola Solutions recommends isolating the
source from the radio with a relay or the use of a suppression diode wired between the source
and ground. Any high current suppression diode that is MR2535 with a breakdown voltage of
between 18 and 40 V suffices. A suitable diode kit is available from Motorola Solutions parts, kit
number HLN6325_.
• If it is required to have the radio power up only through the control head on/off switch, then
connect the ignition sense lead directly to the positive terminal of the battery. This means the
ignition sense is always ignored and a re-wiring is necessary in the future if the operator
chooses any ignition sense CPS setting.
Draft