Motorola Gp3188 Service Manual File

Using a DMM on TP4: if 0V, suspect shorted capacitor C404 (100nF decoupling). If voltage is present but radio is dead, check the microprocessor reset line: pin 7 of U404 (68HC11) must go high (+3.3V) within 10ms of power-on.

The logic board requires a regulated 3.3V from the voltage regulator (IC400). The service manual directs you to test point TP1 (SW B+) — should be battery voltage. Then test TP4 (Vcc Logic) — should be 3.3V. motorola gp3188 service manual

Confirm the battery is charged (>7.0V on DMM). Check battery contacts for corrosion. If OK, proceed. Using a DMM on TP4: if 0V, suspect