Questions and Answers

Cadillac DTC E30, E52, E98 Q. I have a 1993 Cadillac 4.9 liter engine, I have three trouble codes that came up. E30, E52, E98, your guide tells what it means, but not what it takes to correct them, where do I find that. Thank You, Harvey

A. The reason you don't see what to do to correct the code is simple, I could spend the rest of my life doing diagnostic trees for each and every code. They are there so you have a basic idea what is wrong with the vehicle. Here is a little more detail of what the codes mean.

DTC E30:
The PCM/ECM controls engine idle by increasing or decreasing the throttle opening using the idle speed control motor (ISC). The ISC will be active in controlling idle speed at any time the throttle switch is closed. Code E30 sets because the actual engine speed never reaches desired rpm signifying a slow or failed ISC motor. The ISC motor connector is located behind the alternator.

DTC E52:
This diagnostic test monitors the PCM/ECM long term memory for loss of data. If the battery power or ground are disconnected the code will set. Code E52 indicates that the "long term" memory in the PCM/ECM has been reset. This will be the case whenever power is removed from the PCM/ECM (i.e., disconnecting battery cables, disconnecting PCM/ECM connector, etc.). This code should be "cleared" from memory after restoring the PCM/ECM's power supply.

DTC E98:
This diagnostic test monitors idle speed the status of the Park or Neutral switch for a transition. If idle speed is greater than desired the PCM will retard the spark and set the code.

This code can be driver induced by shifting into gear at a throttle angle of less than 20°with the throttle depressed.

The primary purpose of this code is to detect an action of the driver that could cause a hard shift from Park or Neutral to Drive or Reverse.

Check for code E30 as a slow or inoperative idle speed control (ISC) motor may cause the code to set.

In this case you probably have a bad ISC motor and you tried disconnecting the battery to clear the codes.