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  1. #31
    LTX Regular


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    Aug 2013
    Name
    Gary
    Vehicle
    1998 Trans Am
    Location
    Florida
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    241

    Default

    Use the shbox.com site for your codes. http://shbox.com/1/Dtcs.htm
    Or use the 94 F-car factory service manual.

    DTC 43 is : Knock Sensor (KS) circuit
    DTC 23 is : Intake Air Temperature (IAT) sensor circuit (signal voltage high, low temperature indicated)

    Neither is likely anything to do with the pcm. Check the connectors of both. If ok, replace the sensors.

    1998 Trans Am - LS1/A4 - all stock and almost all original - one owner - driven daily.
    Author of Scan9495, free pc apps 93-95 LT1,94/95 L32: http://ltxtech.com/forums/showthread...light=scan9495

  2. #32
    InActive Member


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    Aug 2016
    Name
    Michael B Brewer
    Vehicle
    1994 Caprice 9c1
    Posts
    16

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    After checking in my Haynes Repair Manual, it says code 43 is the PCM not receiving a knock sensor response. Could it be that the PCM needs reprogrammed?

  3. #33
    LTx Guru


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    Join Date
    Apr 2013
    Name
    Fred
    Vehicle
    1994 Formula - SOLD
    Location
    Central NJ
    Posts
    2,279

    Default

    DTC 43 means the voltage on the single-wire knock sensor circuit is not within the specified range (0.78 - 4.10 volts). Should not affect the starting. When DTC 43 sets, the PCM retards timing based on engine operating conditions, but that's with the engine running.

    Easy to check the circuit. Key on/engine off pull the harness connector of the knock sensor. Measure the voltage between the single conductor in the connector and the engine block. Should be 5 volts. Connector still off the sensor, measure the resistance between the pin on the sensor and the block. Should be about 3,500 - 4,500 ohms. Put the connector back on the sensor, check voltage between the wire and the block, should be in the range of 1.5 - 3.5 volts.

    In general, it's better to use LT1-specific sites like Shoebox, rather than Haynes or Chilton.
    SOLD - GONE TO A (VERY) GOOD HOME ! - 94 Formula A3+1: 381ci forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / CC solid roller / TH400+GearVendors OD / 4.11 Strange 12-bolt / 300-shot N2O / Spohn Suspension / roll bar / MoTeC M48 Pro engine management system /a few other odds 'n ends.

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