Coolant Temperature Gauge Needle Does Not Move At All

Check for fuel and emissions-related DTCs.
If you find any, repair the problem, and clear the DTC before continuing.
Jump the SCS line with the Honda Diagnostic System (HDS).
Turn the ignition switch OFF.
Disconnect PCM connector B (56P).
Connect the PCM connector terminal B6 to body ground with a jumper wire.

Fig 1: Connecting PCM Connector Terminal B6 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Turn the ignition switch ON (II).
After 30 seconds or more, does the temperature gauge needle move to the hot mark?
1. YES - Check connections. If OK, substitute a known-good PCM and recheck (see PCM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away, replace the original PCM.
2. NO - Go to step 7.
Turn the ignition switch OFF, and disconnect gauge assembly connector B (18P or 22P*).
*: '04-06 models
Check for continuity between PCM connector terminal B6 and gauge assembly connector terminal B3 (or B5*).
*: '04-06 models

Fig 2: Checking Continuity Between PCM Connector Terminal B6 And Gauge Assembly Connector B3 ('03 Model)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Fig 3: Checking Continuity Between PCM Connector Terminal B6 And Gauge Assembly Connector B5 ('04-06 Models)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Replace the fuel and temperature gauge assembly or the printed circuit board (PCB) ('03 model) or replace the gauge assembly ('04-'06 models).
2. NO - Repair open in the wire between PCM connector terminal B6 and gauge connector terminal B3 (or B5*).
  *: '04-'06 models