Open Circuit - Intermittent Rich Operation, DTC 15 Or 38
Bulletin No. T 85-108AFile in Group 6E
Number 19
Corp. Ref. No. 805-5220
Date Dec. '85
SUBJECT: OPEN CIRCUIT MAT OR COOLANT SENSOR CONNECTORS RESULTING IN INTERMITTENT RICH OPERATION, ERRATIC TCC OPERATION, AND/OR CODES 15 OR 38
MODELS AFFECTED: 1980 ELDORADOS AND SEVILLES WITH 6.0L DEFI ENGINE 1981 FLEETWOOD BROUGHAMS, DE VILLES, ELDORADOS AND SEVILLES WITH 6.0L DFI ENGINE 1981-84 LIMOUSINE WITH 6.0L DFI ENGINE 1982-1985 FLEETWOOD BROUGHAMS, DE VILLES, ELDORADOS AND SEVILLES WITH HT4100 DFI ENGINE 1983-1984 CIMARRONS 1985 FWD FLEETWOODS AND DE VILLES WITH HT4100 DFI ENGINE 1985 FWD LIMOUSINE WITH 4.1L DFI ENGINE
This bulletin supersedes 85-108, Group 6E, which should be destroyed.
Some 1980-1985 vehicles with fuel injection may experience intermittent rich operation, black smoke during restarts, erratic [1][2]Torque Converter Clutch engagement and disengagement, and/or ECM diagnostic codes 15 or 38. These conditions can result from an open circuit or excessive resistance in the Manifold Air Temperature (MAT) and/or coolant sensor circuits. These conditions can be diagnosed by using diagnostic engine data display parameters P.0.4 and P.0.5. Display parameter P.0.4 (coolant temperature) and observe the parameter while an assistant moves or manipulates the coolant sensor wire harness connector. An open circuit condition will cause the coolant temperature to read an unrealistically low temperature (i.e., 0~C, -38~C etc.). Repeat this procedure with parameter P.0.5 (MAT). An open circuit in the MAT circuit will also result in an unrealistically low temperature reading. The coolant temperature should not vary rapidly under steady throttle conditions.
To correct the above conditions, it is necessary to replace either the MAT sensor and MAT connector or the coolant sensor and coolant connector with Metri-Pack type connectors.
The following part numbers are required to equip a vehicle with the new Metri-Pack connectors.
PART NAME PART NUMBER
Coolant Sensor 25036708
Coolant Sensor Wire Harness Kit 12046623
MAT Sensor 25036751
MAT Sensor Wire Harness Kit 12046624
To replace the MAT and coolant wire harness connectors, refer to the attached instructions on wire splicing and soldering.
IMPORTANT: The MAT and coolant wire harness connector wires must be spliced and soldered. Do not use solderless lock type connectors to secure the wires.
Coolant and MAT sensors with the old style connectors are still available from GMWDD. It is important to specify Metri-Pack type connectors if an intermittent problem is suspected.
SPLICING INSTRUCTIONS FOR MANIFOLD AIR TEMPERATURE (MAT) OR COOLANT TEMPERATURE METRI-PACK@ WIRE HARNESS CONNECTOR SERVICE KIT
The Manifold Air Temperature (MAT) or Coolant Temperature sensor must be replaced when a MAT or coolant wire harness connector service kit is installed on a vehicle which does not have a Metri-Packo (flat connector pin) MAT or Coolant sensor. The sensors should be ordered using the following part numbers:
MAT Sensor 25036751
Coolant Sensor 25036708
IMPORTANT: Due to the very low currents in the MAT and coolant circuits, it is very important to solder the wire splice joints to ensure good electric conductivity.
Step One: Open the Harness
If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores).
If the harness has a plastic conduit, simply pull out the desired wire.
Step Two: Cut the Wire
With the wires pulled out of the plastic conduit, cut the first wire at least three inches into the conduit to ensure that the sphce will be protected by the conduit. Cut the second wire 1 1 /2 inches further into the conduit, or 4 1/2 inches from the end of the conduct.
Step Three: Strip the Insulation
If you aren't sure of the wire size, start with the largest opening in your wire stripper and work down until you get a clean strip of the insulation. Be careful to avoid nicking or cutting any of the wires.
Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat the procedure on a new section of wire. The two stripped wire ends should be equal in length.
Figure 1 - Centering the Splice Clip:
Step Four: Crimp the Wires
Locate the clip contained in the service kit. Select the correct anvil on the crimper. (On most crimpers your choice is liniited to either a small or large anvil.) Overlap the two stripped wire ends and hold them between your thumb and forefinger as shown (see Figure 1). Then, center the splice clip under the stripped wires and hold it in place. .
Figure 2 - Crimping the Splice Clip:
- Open the crimping tool to its full width and rest one handle on a firm flat surface.
- Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip.
- Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes (see Figure 2).
Before crimping the ends of the clip, be sure that
- The wires extend beyond the clip in each direction, - No strands of wire are cut loose, and
- No insulation is caught under the clip.
Figure 3 - Completing the Crimp:
Crimp the splice clip again, once on each end. Do not let the crimping tool extend beyond the edge of the chp or you may damage or nick the wire (see Figure 3).
Figure 4 - Applying the Solder:
Step Five: Solder
Apply 50/50 rosin core solder to the opening in the back of the clip as shown (see Figure 4). FoHow the manufacturer's instructions for the solder equipment you are using.
Figure 5 - Good:
Figure 6 - Bad:
Step Six: Tape the Splice
Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires (see Figure 5). Do not flag the tape. Flagged tape may not provide enough insulation, and the nagged ends will tangle with the other wires in the harness (see Figure 6).
Step Seven: Reinstall Wire in Conduit or Retape Harness
For warranty purposes use the following labor operations and times when installing Metri-Pack type sensors and connectors:
T6127 - Replace Coolant Sensor and Coolant Connector 80 E/K - .7 hr. 81 C/E/K - 1.2 hr. 82-83C, 84-85D - .5 hr. 82-85 E/K - .5 hr. 83-84 J - .7 hr. 85C - .6 hr.
T6129 - Replace MAT Sensor and MAT Connector 80-85 E/K - .5 hr. 81-83C, 84-85D - .5 hr. 85C - .6 hr.