SES Light Due To A P1174 DTC - Perform Injector Test With AFIT - CH47976 - keywords active balance cylinder engine fuel injector lamp light misfire miss P0300 test tester

This PI was superseded to include reference to the AFIT user guide and a related Techlink Article. Please discard PIP4017.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

On rare occasions, a SES light may be encountered due to a P1174 DTC. In some instances, a P0300 may also be stored. This may be due to a fuel injector concern on one of the cylinders that a Tech 2 fuel injector balance test may not isolate.

If the SI diagnostics do not isolate a cause for this concern, use the Active Fuel Injector Tester (AFIT - CH47976) to perform an "Injector Test" as outlined in the AFIT User Guide. The AFIT "Injector Test" measures the flow characteristics of all fuel injectors, which is more precise when compared with the standard Tech 2 fuel injector balance test. As a result, the AFIT is more likely to isolate the cause of a P1174 DTC if it is being caused by a fuel injector concern.. The CH-47976 (Active Fuel Injector Tester - AFIT) can also be used to measure fuel pressure and fuel system leak down.

Also, as mentioned in the P1174 SI diagnosis, if the misfire current counters or misfire graph indicate any misfires, it may be an indicator of the cylinder that is causing the concern.

Important: As mentioned in the AFIT User Guide, vehicles that are not listed in the AFIT menu can still be tested with the AFIT. Depending on the model, it may be possible to enter the previous model year and proceed with testing using the DLC connection. If this is not possible on the model that you are working on, it will be necessary to use the direct connection method outlined in the AFIT User Guide (See Pages 16-31).

Notice: If interested, the June 2006 Edition of Techlink contains more information about the AFIT. To find this article, take the following path: Go to GM Dealerworld>> Click on the Service Tab in Dealerworld>> Click on the GM Techlink Hyperlink>> Click on the Archives Hyperlink at GM Techlink>> Click on 06-2006 in the Archives Section>> Click on the Active Fuel Injector Tester Link in the June 2006 Techlink Article.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.