Setting Code 53
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Instructor
Joined: Sep 2003
Posts: 140
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From: charleston sc
Setting Code 53
My 1993 troubleshooting continues - I am setting a DTC 53 (System Voltage) - the code disables all outputs from the ecm effectively rendering the car inoperable. The factory manual says to check the voltage at pin B10 on the ECM with the car idling at 800 RPM - CATCH 22 - the code disables outputs from the computer so how can you get the car to idle at 800 RPM? The code sets if the voltage drops below 8.0 or goes above 17.1 - If I reset the codes in the ECM then try to start the car, it sets the codes right after start up - basically it is setting the code immediately - never giving the computer a chnace to check the voltage. Could the computer be bad? Could it sense a voltage issue that quick? - Hate to replace the ECM if that is not the problem since I doubt any parts dealer is going to take it back if problem is not corrected. Anyone have a thought? Thanks.
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
My manual shows the pin at the ECM is the Green connector pin 12.
That's a switched 12 volts to the ECM from the 5 amp ECM fuse on the side of the I.P.
There should be 12 volts at this fuse when the key is in run or start. Verify the fuse is good.
With the engine off and the ignition key in run, measure the voltage at the 5 amp ECM fuse to ground.
Should be battery voltage.
If that checks out, disconnect the wires going to the alternator (disable the alternator) and start the engine and see if the code sets. If it doesn't set a code, the regulator in the alternator may be bad.
That's a switched 12 volts to the ECM from the 5 amp ECM fuse on the side of the I.P.
There should be 12 volts at this fuse when the key is in run or start. Verify the fuse is good.
With the engine off and the ignition key in run, measure the voltage at the 5 amp ECM fuse to ground.
Should be battery voltage.
If that checks out, disconnect the wires going to the alternator (disable the alternator) and start the engine and see if the code sets. If it doesn't set a code, the regulator in the alternator may be bad.
Last edited by Hooked on Vettes; Aug 15, 2004 at 08:41 AM.
