ECM - Modification of TPS Values/Fuel Pump Operation
TSB No. TS 4-21 11016(R)Section Title: Engine
Division: Automotive
Category: Technical
SUBJECT:
MODIFICATION OF FUEL PUMP OPERATING CONDITION AND TPS VOLTAGE BY THE ECM
MODEL:
SIDEKICK SPORT
YEAR:
NOVEMBER 1995 PRODUCTION AND LATER
CONDITION:
^ Incorrect TPS output value when using Tech- 1.
^ Change in fuel pump operation logic.
^ Modification of ECM.
CAUSE:
N/A.
CORRECTION:
When performing diagnostics and adjustments on the TPS and fuel pump, please use the information listed in this bulletin.
REVISION:
^ Change in TPS output voltage display when using Tech-1.
^ Change in operation logic of fuel pump when the ignition switch is in the "ON" position.
This bulletin is to inform you of the modifications to the ECM which have been carried out since November 1995 production. There have been two revisions to the ECM: LATE style type A1 and LATE style type B1.
Two modifications have been incorporated into the most current (B1) LATE style ECM. The modifications incorporated into the B1 type LATE style ECM include:
^ Change to ECM to allow correct display of TPS voltage when using Tech-1.
^ Change to fuel pump operation logic to enable fuel pump operation for 3 seconds after the ignition key is turned to the "ON" position.
One modification has been incorporated into the A1 type LATE style ECM. This modification includes:
^ Change to ECM to allow correct display of TPS voltage when using Tech-1.
To determine which modifications have been incorporated into the ECM in your vehicle please note the starting VIN numbers listed below for each modification and allow the necessary diagnostic procedures as listed in this bulletin.
EARLY/LATE TYPE IDENTIFICATION
Both the EARLY and LATE type ECM can be identified by the ECM Name Plate affixed to the face of the ECM, as shown.
PARTS SUPPLY DATA
FUEL PUMP OPERATION
Depending on the type of ECM installed in the vehicle, fuel pump operation will vary. Please note the differences between the various types, as listed below:
EARLY TYPE and A1 style LATE TYPE
The ECM will activate the fuel pump when it receives a signal from:
^ The engine starter circuit
^ The CMP (Camshaft Position) sensor
B1 style LATE TYPE
The ECM will activate the fuel pump when it receives a signal from:
^ The engine starter circuit
^ The CMP (camshaft position) sensor
^ The ignition switch "ON" position (The fuel pump will operate for 3 seconds when the ignition switch is initially turned on to time "ON" position)
NOTE:
The fuel pump on vehicles equipped with both EARLY type and A1 style LATE type ECM's will not operate the fuel pump when the engine is not running and the ignition switch is turned to the "ON" position. To activate the fuel pump without cranking or starting the engine, insert a jumper wire into terminals E128A (P/B wire) and E128-1 (B/W wire) of the fuel pump relay coupler.
CAUTION
The fuel pump relay jumper wire procedure described is for temporary, diagnostic purposes only. Be sure to remove the jumper wire when finished with the diagnostic inspection. Failure to remove the jumper wire will allow the fuel pump to activate automatically and continuously whenever the ignition key is turned to the "ON" position.
SERVICING OF THROTTLE POSITION SENSOR
The TPS on vehicles equipped with the EARLY style ECM should not be adjusted using the Tech-1 indication. On vehicles equipped with these ECM's, the Tech-1 will erroneously display a TPS voltage approximately 0.5 volts lower than the actual voltage output from the TPS. To check and/or adjust the TPS on these vehicles, use a digital voltmeter. Refer to the 1996 SIDEKICK SUPPLEMENTARY SERVICE MANUAL (99501-61A20-33E) for the adjustment procedure. Vehicles equipped with the B1 style LATE style ECM display the correct TPS voltage with the Tech-1 and may be serviced in the normal manner.