I have a 99 v6 accord that I put the engine out of a 01 in. I swapped ecu and wire harness. Everything works great except the temp gauge. I know the 99 has 1 sensor for the temp and the 01 has 2. But I am unsure of what to do to get the gauge working.
Any help is appreciated

 

It's the opposite regarding the number of sensors between the 99 and 01 V6. On the ’01 Accord, the coolant temperature gauge and ECM/PCM are controlled by a single ECT (engine coolant temperature) sensor. The 99 had two sensors: a coolant temperature sending unit for the gauge, and an ECT sensor for the ECM/PCM.

1. Is the Yel/Grn wire from the ECM/PCM properly connected at terminal no. 1 of Connector A (32P connector at the ECM/PCM)? The ECM/PCM sends the engine coolant signal via the Yel/Grn wire.

2. Does the Yel/Grn wire make a proper connection at the gauge assembly?

3. With ignition ON (II), there should be pulses on the Yel/Grn wire.

 

Looking at the diagram for the 99 and the 01, the 99 accord temperature gauge in the dash is controlled by a temperature sending unit. The 01 temperature gauge is controlled by the PCM (engine computer).

Which wire harness was replaced when you swapped the engine and PCM?

 

I cant quite remember but I know the motor is from an 01. I think the harness from a 00 and the computer was possibly from a 01.
Its been a while since I actually did the swap. So with the car on should I just use a tester on the yel/grn wire and see if its getting a reading

 

Yes, with the ignition switch in the ON (II) position, you can test for a pulse signal at the Yel/Grn wire.

1. At the green Connector C (16P connector on right side) of the gauge assembly, terminal no. 2, check for a pulse signal.

2. If there is no pulse signal on the Yel/Grn wire at the gauge assembly end of the harness connector, then check for a pulse signal at the Yel/Grn wire at the ECM/PCM side (terminal no. 1 of Connector A - 32P connector). -- You may have to backprobe the ECM/PCM harness side.

3. If there is a pulse signal at the ECM/PCM; but, not at the gauge assembly end, then you would unplug both ends of the harness connector, and then test for continuity of the Yel/Grn wire by using an ohmeter/multimeter by touching the leads at both ends of the harness connectors.

The harness wires that go between the ECM/PCM and gauge assembly for the temperature gauge, goes through a separate 16P gray connector (located behind the driver's dash lower cover).