Engine Controls - ECCS Checker Box: Overview
86nissan05Models 1987 Nissan Models
Section Engine Fuel
Classification EF86-007
Bulletin No. TS86-109
Date June 18, 1986
ECCS CHECKER BOX, 1987 NISSAN MODELS
APPLIED MODELS: All 1987 and later Nissan Models except some early production 1987 Sentra Coupe (B12) vehicles
INTRODUCTION
The ECCS Checker Box may be used to control and read the self-diagnosis systems on most 1987 and later Nissan vehicles equipped with ECCS (Electronic Concentrated Engine Control System). It's an easy tool to use--simply plug it into the "check connector" located under the left side of the dash or at the fuse block, start the engine and allow it to warm up to operating temperature, then use the Checker Box switch to trigger each of the self-diagnosis "modes." You can read the red and green light-emitting diode (L.E.D.) codes in the Checker Box, so it is not necessary to remove the vehicle control unit. The Checker Box also has an audible tone for each L.E.D. signal, so you can "hear" the codes during a road test if you wish--and keep you eyes on the road.
There are five "modes" of self-diagnosis built into all Nissan models that can use the ECCS Checker Box. See the appropriate Nissan service manual for diagnostic details in each case. The ECCS Checker Box will use an electronic signal from its switch to trigger each "mode," and it will indicate the "mode" you're in with a numerical read-out.
SUMMARY OF THE FIVE "MODES" OF ECCS SELF-DIAGNOSIS
Mode 1: In this mode, the control unit monitors the mixture ratio feedback signal from the exhaust gas sensor. Assuming the engine is warmed up and in "closed-loop" operation, a flashing green L.E.D. indicates that the control unit is receiving a mixture ratio signal from the exhaust gas sensor and that the control unit is responding. Refer to the appropriate Service Manual for details.
Mode 2: In this mode, the red and green L.E.D.s flash to indicate the mixture ratio. If the L.E.D.s flash simultaneously, or very nearly simultaneously, they indicate that the engine air-fuel mixture is in the correct range for best efficiency of the 3-way catalytic converter. Refer to the appropriate Service Manual for details.
Mode 3: In this mode, the self-diagnosis system recalls any gross electrical malfunction (extremely low current draw, or extremely high current draw) that has occurred in the ECCS system and displays a code to indicate the circuit in which it appeared. Refer to the appropriate Service Manual for the specific codes and follow-up testing procedures.
Mode 4: This mode checks the function of specific on-off switch circuits that serve as inputs to the ECCS system, such as the "Start" signal of the ignition switch, the idle switch, the vehicle speed sensor. Refer to the appropriate Service Manual for details.
Mode 5: This mode is called "real-time" diagnosis. It checks several of the most important ECCS sensor circuits, such as the crank angle sensor and the air flow meter, at very high sensitivity. Refer to the appropriate Service Manual for the codes and further information.
PROCEDURE FOR USING THE ECCS CHECKER BOX
The following pages give a general procedure for using the ECCS Checker Box to set the self-diagnosis modes in operation and to read the L.E.D. codes. Once the Box is plugged into the test connector on the vehicle, it can change the modes quickly from one to the other, so it will be simple to check all parts of the ECCS system at one sitting.
WARNING: Plug the Checker Box into the check connector only when the vehicle ignition key is in the "OFF" position, then start the engine. The engine should be fully warmed up before you "read" the self-diagnosis signals at the Checker Box L.E.D.s.