DTC 32

Chart - Code 32 EGR Vacuum Control:

Wiring Diagram for EGR Vacuum Control.:

CODE 32 - EXHAUST GAS RECIRCULATION (EGR) CIRCUIT


Circuit Description:
The Exhaust Gas Recirculation (EGR) Valve is opened by engine vacuum In order to control and monitor EGR application an Electronic Vacuum Regulator Valve is used. The EVRV is composed of two devices:
1. EGR Solenoid, normally closed (Vacuum Blocked).
2. EGR Vacuum Switch, normally open, (No Current Flow).
EGR Vacuum Control is accomplished by the ECM grounding CKT 435. This energizes the EGR solenoid. This is done thousands of times a second. By varing the length of "ON" time, as compared to "OFF" time, Pulse Width Modulation, (PWM), The ECM controls the vacuum source to the EGR Valve. EGR is monitored by the ECM thru the EGR vacuum switch. The EGR vacuum switch, a normally open electrical switch, has an orfice built in, which restricts the vacuum signal to the EGR vacuum switch, when sufficent vacuum reaches the EGR vacuum switch, to close the electrical switch. There should also be sufficient vacuum to open the EGR Valve.

Code 32 will set, if the vacuum switch closes at idle, or, if it does not close under load (less than Wide Open Throttle (WOT).
Engine running.
Scan Tool (load variable or LV8) reading less than 144 cts.
Code 33 or 34 not present
No vacuum to EGR (switch open).
Coolant temperature above 42.5 C (108 degrees F).
Conditions exist over 5 sec. (Turbo 9.6 sec.).



Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. "Scan" displays the condition of the EGR diagnostic switch. In park or neutral, the display should read "NO" (open switch).
2. Under moderate engine load, the display will switch from "NO" to "YES".
3. Checks the integrity of the 12 volts feed and ground circuits. If these circuits check OK, the fault is elsewhere in the EVRV/EGR Control circuit.
4. A test light connected between terminals "A" and "B" will verify the integrity of the ECM wiring and cheek for proper ECM operation.
5. If "YES" was displayed at idle, disconnect the EVRV harness. If display remains "YES", the fault is either a short to ground in CKT 932 or the ECM.
6. If the EGR display switches from "YES" to "NO" when the EVRV is disconnected, the fault is either in the EVRV/EGR Solenoid, CKT 435 or the ECM.


Probing at terminal "B" will further isolate the fault. If the test light is on, disconnect ECM A-B connector before checking CKT 435 for a short to ground since the short could be inside the ECM.


Diagnostic Aids:

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.
Check For:
Poor Connection or Damaged Harness; Inspect ECM harness connectors for backed out terminal "D9", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Intermittent Test; If connections and harness checks out OK, "Scan" EVRV switch while moving related connectors and wiring harness. If the failure is induced, the "EVRV Switch" display will change. This may help to isolate the location of the malfunction.