Code 43

[csucsi]

i posted in the engine forum already ,so here goes

I got code 43 off the SES light and changed the module in the cap. Then I did a full tune up and the timing with the wire unplugged. I installed a new knox sensor and pigtale, installed new timing chain set and beat myself in the head with a large wrench. I am still getting code 43 - the truck is 1993 K 1500 4wd Suburban with 5.7 - Any help would be greatly appreciated. Thanks

[SPARK CHASER]

i posted in the engine forum already ,so here goes

I got code 43 off the SES light and changed the module in the cap. Then I did a full tune up and the timing with the wire unplugged. I installed a new knox sensor and pigtale, installed new timing chain set and beat myself in the head with a large wrench. I am still getting code 43 - the truck is 1993 K 1500 4wd Suburban with 5.7 - Any help would be greatly appreciated. Thanks

 

If you used a jumper on the ALDL connector to get the code, are you sure you counted the flashes correctly? I have had in the past re-read the SES flashes several times to make sure I got the count right. One time I thought it had flashed the ECM failure code, but after several re-reads I determined it was only flashing the O2 sensor fail code. BIG DIFFERENCE!

 

If this isn't the case, look for a bad wire or make some jumper wires to bypass a possible damaged wire.

[csucsi]

i posted in the engine forum already ,so here goes

I got code 43 off the SES light and changed the module in the cap. Then I did a full tune up and the timing with the wire unplugged. I installed a new knox sensor and pigtale, installed new timing chain set and beat myself in the head with a large wrench. I am still getting code 43 - the truck is 1993 K 1500 4wd Suburban with 5.7 - Any help would be greatly appreciated. Thanks

 

If you used a jumper on the ALDL connector to get the code, are you sure you counted the flashes correctly? I have had in the past re-read the SES flashes several times to make sure I got the count right. One time I thought it had flashed the ECM failure code, but after several re-reads I determined it was only flashing the O2 sensor fail code. BIG DIFFERENCE!

 

If this isn't the case, look for a bad wire or make some jumper wires to bypass a possible damaged wire.

 

 

 

i've been messing with this for 3 weeks now and cleared the code every time and about 10 seconds later its back again

i just replaced the knock sensor all the way back to the bulkhead and installed another new sensor just in case ...wellsee what tommorow brings

 

does anyone have an FSM for this truck???

[TBLAZER]

i posted in the engine forum already ,so here goes

I got code 43 off the SES light and changed the module in the cap. Then I did a full tune up and the timing with the wire unplugged. I installed a new knox sensor and pigtale, installed new timing chain set and beat myself in the head with a large wrench. I am still getting code 43 - the truck is 1993 K 1500 4wd Suburban with 5.7 - Any help would be greatly appreciated. Thanks

 

If you used a jumper on the ALDL connector to get the code, are you sure you counted the flashes correctly? I have had in the past re-read the SES flashes several times to make sure I got the count right. One time I thought it had flashed the ECM failure code, but after several re-reads I determined it was only flashing the O2 sensor fail code. BIG DIFFERENCE!

 

If this isn't the case, look for a bad wire or make some jumper wires to bypass a possible damaged wire.

 

 

 

i've been messing with this for 3 weeks now and cleared the code every time and about 10 seconds later its back again

i just replaced the knock sensor all the way back to the bulkhead and installed another new sensor just in case ...wellsee what tommorow brings

 

does anyone have an FSM for this truck???

 

Ok,see if this will help you,this is from an online service manual.

Circuit Description:

The DTC 43 circuit consists of a knock sensor with one wire that goes directly to the PCM. There are two DTC 43 checks performed by the PCM. One check consists of monitoring CKT 496 for a voltage that is more than 4.5 volts and less than .64 volt.

 

If voltage is either too high or too low, for 10 or more seconds, DTC 43 will set. Once engine temperature reaches 87.5°C or more, but not over 104°C, MAP above 81 kPa and engine speed below 3200 rpm respectively, the PCM will perform a self check by advancing the timing incrementally while anticipating a knock signal. If no knock signal is received during two consecutive tests, DTC 43 will be set.

 

Test Description:

Numbers below refer to circled numbers on the diagnostic chart.

 

1.The first test is to determine if the system is functioning at the present time.

2.Test two determines the state of the 5 volt reference voltage applied to the knock sensor circuit.

Diagnostic Aids:

The PCM applies 5 volts to CKT 496. A 3.9K ohm resistor in the knock sensor reduces the voltage to about 2.5 volts. When knock occurs, the knock sensor produes a small AC voltage that rides on top of the 2.5 volts already applied. An AC voltage monitor in the PCM is able to read this signal as knock and incrementally retard spark.

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Ok,Here is more info on that,

circuit 496 is the voltage coming from the computer terminal B15 to the knock sensor.

 

Check voltage at the computer B15 terminal with the sensor connected and the engine at idle.

 

If the voltage is 5V, disconnect and check the knock sensor if withing spec's(3.9K) then you have a faulty connector at the sensor or an open on circuit 496,(this is the wire from the computer to the knock sensor),if out of spec's then you have a faulty knock sensor.

 

If the voltage at the computer terminal B15 is 2.3 to 2.8 and the sensor is withing spec's then the prom(mem-cal) or the computer is faulty.

 

If the voltage is .4V or less then disconnect the knock sensor and if the voltage goes to 5V then you have a faulty knock sensor,if the voltage is .4V or less then you have a short on circuit 496 or a faulty computer.

 

This is from a trouble shooting chart and it applies if you have 4L60E electronict transmission .