C.E. Niehoff & Co. C505 Troubleshooting Guides - Manual (Page 6)

Page 6 TG70C
Section C: On-Vehicle Troubleshooting
A2-334 and A2-335 Regulator Troubleshooting
A2-334 regulator is mounted directly to the outside of the alternator. A2-335 regulator is mounted remotely on the
vehicle and connected to alternator with extended wiring harnesses.
Main diagnostic feature of regulators consists of a tricolored (green, amber, red) LED located on the end of the regulator.
The LED works like a voltmeter, measuring charging voltage. See Table 3 for diagnostic features and LED explanations.
LED COLOR STATUS
TABLE 3 – A2-334 & A2-335 Regulator LED Diagnostics with Engine On*
Alternator and regulator operating normally. GREEN Solid
Low system voltage — Electrical load exceeds
alternator rating at present rotor speed.
ACTION
No action required.
Replace alternator.* AMBER Flashing *
System voltage higher than setpoint. May occur during normal load switching. RED Flashing
Alternator fault — No output.*
When loads decrease or speed increases, LED
should be solid GREEN. If not, check drive belt
and charging system connections.
Solid
A2-343, A2-348, and A2-350 Regulator Troubleshooting
A2-343 and A2-348 regulators are mounted directly to the outside of the alternator. A2-350 regulator is mounted
remotely on the vehicle and connected to alternator with extended wiring harnesses.
Main diagnostic feature of regulators consists of a tricolored (green, amber, red) LED located on the end of the regulator.
The LED works like a voltmeter, measuring charging voltage. See Table 4 for diagnostic features and LED explanations.
These regulators have OVCO (overvoltage cutout) that will trip at vehicle electrical system voltage above 16 volts that
exists longer than 3 seconds. OVCO feature detects high voltage and reacts by signaling relay in alternator field circuit
to open. This turns off alternator (LED is flashing RED). OVCO circuit is reset when engine is restarted or when system
voltage drops to 11.5 V. Regulator then regains control of alternator output voltage.
An additional temperature-voltage sense/J1939 harness may or may not be used with the A2-343, A2-348, and A2-350
regulators:
• When optional temperature-voltage sense/J1939 harness is not connected, regulator will operate in fixed voltage
setting determined by the select switch position on the bottom of the regulator (see page 2).
• When optional temperature-voltage sense/J1939 harness is connected, regulator will automatically optimize the
charge voltage for battery type selected based on temperature. See page 2. Also, vehicle manufacturer-requested
functions of J1939 interface are available through connector.
LED COLOR STATUS
TABLE 4 — A2-343, A2-348, & A2-350 Regulator LED Diagnostics with Engine On*
Alternator and regulator operating normally. GREEN Solid
Low system voltage — Electrical load exceeds
alternator rating at present rotor speed.
ACTION
No action required.
When loads decrease or speed increases, LED
should be solid GREEN. If not, check drive belt and
charging system connections.
Replace alternator.*
AMBER Solid
High system voltage – May occur during
normal load switching.
Indicates voltage above setpoint but below OVCO
threshold (less than 16 volts).
Indicates voltage exceeds 16 V for more than
3 seconds. System diagnosis required. See “OVCO
Troubleshooting” section on page 7.
RED Solid
Alternator fault — No output.* Flashing*
Flashing OVCO tripped.
No power to ignition or regulator is defective. OFF Go to Chart on page 8.
* LED will flash AMBER for one minute upon start-up/shutdown—if regulator does not sense alternator rotation, regulator will time out.
No power to ignition or regulator is defective. OFF Go to Chart on page 8.
* LED will flash AMBER for one minute upon start-up/shutdown—if regulator does not sense alternator rotation, regulator will time out.