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by Bob O’Neill and Bob Lincoln
On all L-bodies (Omni/Horizon and related cars), along with all vehicles from model years before 1987 with EGR (nearly all of them), code 34 indicates that the EGR solenoid circuit is open or shorted — as indicated by voltages of 0 volts when the solenoid is on, or voltage of 12V when the solenoid is turned off. The power limited light will not be lit and the system will not enter limp mode.
On 1987 and newer vehicles except L-bodies, code 34 triggered when the voltage of 0V or 12V not detected when the cruise control (speed control) solenoid is turned on or off, respectively; this indicates a short or break in the system.
Possible Reasons for Code 34
Poor wiring or connection - Read the page ‘How to troubleshoot drivability issues’. Check the wiring and connections from the logic module to the solenoids. Clean and re-grease the connectors with dielectric grease.
Defective solenoid (L-bodies 1987 and earlier) - The solenoids are located in the right, front fender in a cluster of up to 4 solenoids. If a signal from the harness to the solenoid measures 12vdc when the solenoid is off the solenoid will need to be repaired or replaced. See Solenoids-101 for information about how solenoids work and how to test them.
Defective solenoid (other vehicles) – The speed control servo is located under the hood. On earlier models it is located under the battery. On later models it is located near the strut tower. This unit will require disassembly and testing. The solenoid inside the speed control ‘unit’ is different than other solenoid but check Solenoids-101 for details about solenoids.
Sensors, Switches, and Other Systems | Main Repairs Page | EEKs
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