Initial Inspection and Diagnostic Overview

***UPDATED BY TSB #83-3-25

CALIBRATIONS: 1-63T-R15,1-64T-R16,2-63Y-R14,2-64Y-R15

Approximately March 1, 1983, the 5.8L engine calibrations used in under 8500 lb. GVW Light Trucks were revised to the above listed calibration levels. These new calibrations require a new procedure for conducting the "quick test"/"self-test". Failure to use the new testing procedures will cause a properly functioning system to produce a code 44 rather than the correct code of 11. The new test procedures, if followed correctly on a properly functioning system, will produce code 11.

Apply the following revisions to determine if the EEC system used on the above calibrations is functioning properly. NOTE: Do not use this revised procedure on other than the listed calibrations.

QUICK TEST PROCEDURE

The new calibrations delete the EEC III Throttle Kicker control on the subject engines, so changes must be made to the following EEC III Quick Test and Pinpoint Test steps.

A. Step 15 - Disregard parts on "KS Light Pattern" and do not go to section J.

B. Step 18 - Disregard the parts on "TKS Lights & TK Movement". To indicate self-starting, observe TAB and/or TAD lights. If either or both of these lights begin turning on and off within a minute, go to Step 19. If both lights do not turn on and off, replace the processor and retest. If not OK, replace the calibration assembly using the original processor and retest. Do not go to Steps J8 or J11.

C. Step 19 - Disregard the parts on "TK Extended" and use the TAB or TAD lights as outlined for Step 18.

D. Step 22 - Disregard the parts "TKS Lights Switching". To indicate self-test is complete, look for 2 pulses on both TAB and TAD lights, then go to Step 23. If both lights never pulse twice (allow 3 minutes after starting self-test) replace calibration assembly. Do not go to Step J16.

PINPOINT TEST

E. Section J Throttle Kicker- Disregard Steps J1 through J16. Do not use any of these steps for these calibrations. It is still permissible, however, to use Steps J17 and J18.

F. Step N2 - If idle within specification, do not go to step N3 but instead go to Step N4.

G. Step N3 - Disregard this step and do not use for these calibrations.

NEW SELF-TEST PROCEDURE

As previously mentioned above, if the following procedure is not followed, a code 44 will be produced which is not a firm indication that the system is functioning properly. It should also be noted that if the new test procedure is not used, and the system produces code 11, the system is not operating properly and the following checks should be made: verify that vacuum hoses are properly connected and that no leaks are present, that no "shorts-to-ground" exist in Circuit 100 or the TAB Solenoid (Key On-Engine Off) and that the Thermactor System and its components are functioning properly.

A. After connecting the EEC III tester, disconnect the vacuum cap from the "TEE" at the thermactor bypass valve. Remove the manifold vacuum line (black with red trace) from the air cleaner bi-metal sensor and install a 5/32" vacuum connector in the end of the hose. Connect approximately 2 ft. of 5/32" hose between the connector and tee.

B. Proceed with Quick Test at step 3. The only difference that will be seen is with the Throttle Kicker, as previously described. An 11 service code will be generated if the EEC III system is OK. If any other service codes are displayed, including also a 44 code, go to the referenced pinpoint test.

C. After all testing and/or services are done, remove the 2' test hoses and 5/32" connector, re-cap the tee at the bypass valve and re-install manifold vacuum to the air cleaner bi-metal.

Fig. 1 How to use Diagnostic Procedure:

This diagnostic procedure is only used on Electronic Engine Control (EEC-III) equipped vehicles and only when the Diagnostic Routines instruct you to perform EEC-III Diagnostics. Most of the time the Quick Test can detect total engine system malfunctions that are both EEC System related and non-EEC System related. The Quick Test accomplishes this by excercising EEC System components and looking for a corresponding engine response. If the malfunction is EEC System related, the Pinpoint testing will result with the correct malfunctioning EEC System component being replaced. However, if the malfunction is not EEC System related, the Quick Test will detect an improper engine malfunction, and the ensuing Pinpoint testing may incorrectly indicate an EEC System component as being responsible. To prevent EEC Pinpoint testing from misdiagnosing an EEC System component when a non-EEC System failure has actually occurred, attention should be paid to Diagnostic Routines. Refer to Fig. 1 for detailed information on how to use this diagnostic procedure.

To test and service the EEC-III subsystem, perform the Quick Test first, and if the vehicle passes the Quick Test without running any Pinpoint Tests, you will know the EEC-III subsystem is OK and the vehicle's problem exists somewhere else other than in the EEC-III subsystem. However, if a step of the Quick Test fails, run only the Pinpoint Tests specified by the failed step.

If any service to the vehicle is to be performed while running the Quick Test or Pinpoint Tests, do only those services that are specified in either test.

After all tests and services have been completed, repeat the entire Quick Test to make sure the EEC-III subsystem works properly.

To insure proper validation of the Electronic Engine Controls System, do not short cut this procedure, performing all of the Quick Test starting with:

TEST STEP
1 PRE-CHECK PROCEDURES AND VEHICLE PRE-START PREPARATION

THROUGH

TEST STEP
26 EEC-III SELF TEST, OK