"Check Engine" Light/Code 15-Field Fix (93-36-007)

"CHECK ENGINE" LIGHT/CODE 15-FIELD FIX

TECHNICAL SERVICE BULLETIN

"CHECK ENGINE" LIGHT/CODE 15 - FIELD FIX

Model(s): 1990-94 Hyundai Excel

1991-92 Hyundai Scoupe

Group: Engine Electrical

Bulletin No.: 93-36-007

Date: July, 1993

SERVICE INFORMATION

Some 1990-94 Excel and 1991-92 Scoupe models may experience recurrent activation of the "Check Engine" light and setting of fault code 15 in the engine control module (ECM) memory. The vehicle may exhibit stalling at idle and an inoperative air conditioning compressor when this condition occurs.

These symptoms may be related to a poor throttle position (TP) sensor ground circuit in the ECM wiring harness. The field fix procedure for this condition varies according to the wiring harness manufacturer, but basically involves the soldering of a crimp connection.

The connection involved is located where four black ground wires (five in California specification cars) for the throttle position (TP) sensor, idle speed control (ISC) motor position sensor, volume airflow (VAF) sensor, and engine coolant temperature (ECT) sensor (plus the EGR temperature sensor on California spec. vehicles) are joined with two ground wires leading to the ECM.

WIRING HARNESS IDENTIFICATION

There are three manufacturers for the ECM wiring harness: Kyung Shin, Dong Hae, and Yu-Jin.

The manufacturer can be determined by looking at the identification tag wrapped around the wiring harness approximately 4-8" above the ECM connectors. The Yu-Jin has no manufacturer identification. The repair procedure varies according to harness manufacturer because Kyung Shin and Dong Hae use different splice locations and types of splices.

The splice in the Yu-Jin harness varies but is normally on the passenger side of the end of the fuel rail.

SOLDERING TECHNIQUES

The most important step in the repair procedure is the proper soldering of each connection.

1. Use a soldering gun or a high output pencil type soldering iron so this joint can be heated quickly, without transferring too much heat into the wires. Use only thin, rosin core lead solder.
2. Place a block of wood under the splice to be soldered to give a base to push against and prevent the soldering gun or solder from touching other wire.
3. Heat the connector, not the wires or solder.
4. Feed the solder into the end of the connector. The solder will be drawn into the connector, towards the heat. If the solder beads up, the connector may not be hot enough or there may not be space in the connector to draw the solder into it.
5. Feed solder into the connector until the connector appears to be filled.
6. Continue heating the connector for a few seconds after removing the solder to allow good penetration. Check to be sure that there are no sharp points of solder that may rub and cut into outer wires.

SERVICE PROCEDURE - KYUNG SHIN

1. Disconnect the battery ground cable.
2. Under the crash pad on the drivers side, disconnect the ECM wiring harness connectors and ground wires from the ECM. Disconnect the two main wiring harness connectors. Remove the tie strap from around the ECM wiring harness and main wiring harness.
3. In the engine compartment, disconnect the A/C low pressure switch connector, A/C compressor bullet connector (blue to red wire), distributor connector, purge control solenoid valve connector, EGR control solenoid valve connector (California spec. vehicles only), pre-excitation resistor connector, and the ground wires leading to the fire wall (G07 for Excel, G06 for Scoupe). Remove the three bolts attaching the square ECM wiring loom cover to the intake manifold surge tank. Remove the tie strap holding the EGR/purge control solenoid valve wiring to the accelerator cable.
4. Carefully feed the ECM wiring harness under the crash pad and through the firewall grommet opening into the engine compart- ment. Pull the harness completely into the engine compartment.
5. The TP Sensor crimp connection splice is located approximately eight (8) inches from the firewall grommet on the ECM end of the harness. See Fig 1 .
   Fig 1: TP Sensor Crimp Connection Location

   
6. Peel open the wiring harness cover to find the splice. Remove any electrical tape or shrink wrap tubing over the splice.
7. Solder the crimp connector.
8. Re-tape the connection using black electrical tape. Re-wrap the wiring bundle with the original cover.
9. Re-install the wiring harness in its original position. Reattach the square ECM wiring loom cover to the intake manifold surge tank. Reconnect the electrical connectors that were disconnected in steps 2 and 3 and replace the tie straps that were removed. Reconnect the battery ground cable.
10. Verify that all wiring harnesses are clear of moving parts or hot components.
11. Clean off throttle body carbon deposits per procedure given in fuel system section of the appropriate shop manual. Clean TP sensor connectors at throttle body by disconnecting and spraying with electrical contact cleaner.
12. Using the M.U.T., set the idle speed and TP sensor voltage.

Specifications TP Sensor = 480 - 520 mV

IDLE SPEED = 750 RPM

MP Sensor = 900 - 1000 mV

SERVICE PROCEDURE - DONG HAE

1. Disconnect the battery ground cable.
2. Under the crash pad on the driver's side, disconnect the ECM wiring harness connectors and ground wires from the ECM. Disconnect the two main wiring harness connectors. Remove the tie-strap from around the ECM wiring harness and main wiring harness.
3. In the engine compartment, disconnect the A/C low pressure switch connector. A/C compressor bullet/connector (blue to red wire), distributor connector, purge control solenoid valve connector, EGR control solenoid valve connector (California spec. vehicles only), pre-excitation resistor connector, and the ground wires leading to the firewall (G07 for Excel, G06 for Scoupe). Remove the three boil attaching the square ECM wiring loom cover to the intake manifold surge tank. Remove the tie strap holding the EGR/purge control solenoid valve wiring to the accelerator cable.
4. Pull the ECM wiring harness grommet out of the firewall and pull approximately 6 inches of the wiring harness into the engine compartment.
5. The TP Sensor crimp connector splice is between the square ECM wiring loom cover and the firewall grommet. Carefully slice the tape that is wrapped around the corrugate plastic wiring conduit and open up the conduit to expose the splice.
6. Remove the crimp connection by cutting the wires about one inch away from each side of the connector. Pull the wires apart. Strip approximately 1/2 inch of insulation from the end of each wire.
7. Make a jumper harness to replace the crimp connection section that was removed. The jumper should be about the same length as the piece of the connection that was removed. The jumper must be made from a length of black 12 gauge wire that has had 1/2 inch of insulation stripped from each end with a 12 gauge crimp connector fastened at each end. The crimp connectors should be of the solder type with no plastic insulation. Crimp a connector at each end of the jumper wire and then solder them.
8. Insert the two ground wires from the ECM side of the wiring harness into one of the jumper wire connectors and crimp and solder. Insert the four (or five) black wires from the other end of the ECM wiring harness into the other connector of the jumper harness Crimp and solder. See Fig 2 .
   Fig 2: Soldering ECM Side Ground Wire

   
9. Wrap the two solder connectors with electrical tape. Put the wire bundle back into the plastic conduit and re-wrap tightly with electrical tape.
10. Push the wiring harness back through the fire wall and reinstall the grommet. Reconnect all electrical connectors disconnected in steps 2 and 3 and re-attach the square ECM wiring loom cover to the intake manifold surge tank.
11. Verify that all wiring harnesses are clear of moving parts or hot components.
12. Clean off throttle body carbon deposits. Clean throttle body by disconnecting and spraying with electrical contact cleaner.
13. Set the idle speed and TP Sensor.

Specifications TP Sensor = 480 - 520 mV

IDLE SPEED = 750 RPM

MP Sensor = 900 - 1000 mV