Diagnostic Aids:

The speed sensor generates an electrical signal representative of vehicle speed. The vehicle speed sensor buffer amplifies and conditions signal from speed sensor to ECM.

Code "E024" indicates that a speed signal is not being received by ECM when vehicle is in 4th gear. This can be observed in engine date display as a "VEHICLE SPEED" reading (parameter ED12) of zero MPH while driving.

NOTE: The following step numbers refer to the numbers in the accompanying flow chart(s).

To begin diagnosis, determine if speedometer is operating properly. If it is not refer to SPEEDOMETER DIAGNOSIS.
If the speedometer is operating properly, determine if speed signal is being received by ECM. This can be observed by noting the vehicle speed sensor reading (parameter P.1.2.) with the drive wheels turning.
If voltage is 6.5 volts or greater, check for a faulty vehicle speed sensor buffer connector or a faulty speed sensor buffer. If voltage present is 5-6.5 volts, fault is at ECM connector or ECM. Before ECM is replaced, perform PERFORMANCE CHART 1 - ECM REPLACEMENT CHECK at the end of this article.
If output voltage is okay at buffer, check output at ECM terminal A10.