Well this last weekend I was fiddlin' with my 88gta 5.7 and decided to pull the codes, I got a code 43(Low voltage at electronic spark timing circuit). Now I had no idea how to fix this problem so I started by checking that tan wire w/ a black stripe that goes to the dist. wireing looks good and an impedence check verified what I saw. Does this mean I need a new ECM or is it somthing easier?

 

Code 43 -- ESC electronic spark control module.

Electronic spark control is accomplished with a module that sends a voltage signal to the ECM. When the knock sensor detects engine knock, the voltage from the ESC module to the ECM drops and this signals the ESC to retard timing. The ECM will retard the timing when the knock is detected and rpm is above about 900 rpm.

Code 43 means the ECM has been low voltage at CKT 485 terminal "B7" for longer than 5 seconds, with the engine running or the system has failed the functional check.

This system performs a functional check once per start up to check the ESC system. To perform this test the ECM will advance the spark when when coolant is above 95 degrees C(194 Degrees F) and at a high load condition ( near WOT). The ECM then checks the signal at "B7" to see if a knock is detected. The functional check is performed once per start up and if a knock is detected when the coolant is below 95 C then the test has passed and the functional check will not be run. If the function check fails, the SES light will remain ON until the ignition is turned OFF, or until a knock signal is detected.

Ok to test the stuff out to find what is wrong do this.
1.

• Clear Codes
• idle engine for 1 minute or until a SES light comes ON
• read new codes

No code 43
This test will dtermine if the system is functioning at this time. Usually a knock signal can be generated by tapping on the right exhaust manifold. If no knocksignal is generated, try tapping on the block next to the area of the sensor. Follow the following steps.

• run engine at about 1500 RPM
• trans in park/nuetral and at normal operating temp
• tap engine block in area of knock sensor and check for rpm drop

If the RPM drops the problem is intermittent, if there is no rpm drop then there is no problem

But if you do get a code 43
3.with the engine idling check terminal B7 with a VOLTMETER to a ground and note the voltage

If over 6 volts it is a faulty connection at ECM terminal B7 or ECM
If under 6 volts do the following

4. Ignition on, but engine stopped
recheck the voltage at ECM terminal B7
If over 6 volts change the ESC module
If under 6 volts do the following

5. Ignition off
disconnect ECM "A-B" connector
turn ignition on and recheck voltage
If over 6 volts Replace the ECM
If under 6 volts do the following

6. Disconnect ESC module. check voltage from ESC connector terminal B to ground.
It should read battery voltage
If not OK repair open in CKT 439
If OK do the following

Check for open or short to ground in CKT 485. If not open or shorted to ground, it is a faulty esc connection or ESC module.


I hope some of that can help ya. I also got the code once but it was from some bad gas.