How To: H23A/H22/F20B Temperature Gauge for 2000-2002 models

Discussion in 'Engine & Transmission Mods' started by bavarianblessed, Aug 11, 2019.

  1. bavarianblessed

    bavarianblessed Member

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    Oct 7, 2017
    This seems to be a commonly asked question so I thought I would write up what I've learned

    The 00'-02' model F23A Accords use a different circuit and gauge type for the temperature gauge in the cluster. For whatever reason, Honda decided that the ECU should be responsible for driving the temp gauge with a digital signal instead of the previous and much simpler method of a direct connection to the single-pin thermo sensor (part 37750-PH2-014) mounted to the side of the head. The 00'-02' model F23's have a bolt in this spot to seal the hole instead. If you are swapping in an F20B or H motor you'll need to work around this change if you want to use stock temp gauge.

    **You will need to get a 98' or 99' gauge cluster**
    I pulled one at my local LKQ for $30​

    This is my setup:
    • 02' Accord SE Auto - F23A1
    • 01' PDE H23A with MCJA tranny
    • PCF ECU - OBD2b using the original F23A1 harness
    So I'm swapping in a complete SiR Wagon (2WD) drive train and staying OBD2b for emissions compliance.

    The F23A1 uses a VTEC pressure signal switch located next to the VTEC solenoid and the 2-pin water temp sensor on the side of the head here

    Since the H23A doesn't use a pressure switch this plug isn't used and since it's also located right next to the thermo sensor I clipped the connector off. You have a Blue/Blk and Brown/Blk wire there now, tape off the Brown/Blk wire, it's the sensor ground signal and not needed. The Blue/Blk wire is then soldered to the thermo sensor connector from the hacked H23 harness I got with my swap.

    Once that was done I moved inside the car to finish the connection.
    On the C connector at the ECU I de-pinned C10 and C24

    C10 is the other end of that VTEC pressure switch that now has the thermo sensor connector on it
    C24 is the coolant temp signal output from the original PAA ECU

    Neither pin is used by the PCF ECU I'm installing and C24 will only have a wire in place on the 00'-02' models.
    Once they are de-pinned clip the connector off each wire and strip the ends to twist and solder together

    The other end of that Yellow/Grn wire from C24 connects directly to the gauge cluster on the cluster harness at pin C2

    Once completed you will have a direct connection from the thermo sensor to your 98' or 99' gauge cluster. As long as you properly solder (and strain relief) or crimp your connections the circuit impedance will be negligible and shouldn't affect your temp readings at the gauge. I measured resistance between the thermo connector under the hood and C2 at the gauge harness and got this

    This is what I did to make it work and the info for the wiring and gauge cluster differences was obtained from a few different posts here and from studying the Helms manual so I'm not an expert. If anyone has questions though ask away, I'll try to help :beer:


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