GE LTC MAP User Manual

Refer to Table 5-1 for common troubleshooting procedures. 

Table 5-1: Common Troubleshooting Procedures 

Incorrect Temperature Reading on a 

4-20 mA Channel. 

Defective sensor. 

 

Loose wiring connection from sensor 

to circuit board 

 

 

Defective circuit board. 

 

Ribbon cable between CPU and I/O 

circuit boards loose. 

 

 

 

 

Ground loop exists with another 

connection. 

 

Swap suspect sensor with a known good sensor. 
Check wiring connection from the sensor to the 

circuit board; ensure that the wire is correctly 

inserted into the screw down connector block. 

Swap suspect circuit board with a known good 

board. 

Temporarily move the suspect RTD sensor wire to 

an unused 4-20 mA channel to determine 

whether fault follows sensor or circuit board. 

Inspect ribbon cable connection at CPU board and 

at I/O board. 

Systematically remove other connections to the 

circuit board until the cause of the loop is found.  

For example, problems may be caused having 

the individual wire (color) order incorrect for the 

cable between the control isolator and the I/O 

board. 

Unrecorded tap change events. 

Incorrect wiring. 
Incorrect parameter settings. 

Check wiring diagram and installation. 
Check event start and stop parameters. 
Check for a minimum motor current parameter. 

Incorrect Current Readings. 

Incorrect installation. 
No current present. 
Incorrect parameter settings. 

Check wiring diagram and installation. 
Verify current with a handheld meter. 
Check CT Ratio. 
Check Calibration Parameters. 

Incorrect Voltage Readings. 

Incorrect wiring. 
Incorrect parameter settings. 
Power glitch. 

Check wiring diagram and installation. 
Check Calibration Parameters. 
Cycle Power.