KNOWN PROBLEM AND SOLUTION
A 2002 Chevy Impala has the ABS malfunction light on and wheel speed sensor code, C0040 – Right Front Wheel Speed Circuit Malfunction, is in the scan tool. There is no apparent damage to the harness or connectors. TSB #03-05-25-008 states that the connector for the sensor and its harness wiring need to be replaced. You can obtain the parts from a dealer and complete the repair. As a precaution, the wheel bearing should be inspected, as it could be a part of the problem.
PROBLEM SOLUTION AND COMPLICATIONS TO THE SOLUTION
A vehicle has the ABS malfunction light on. Wheel speed sensor codes, C0400 – Right Front Wheel Speed Circuit Malfunction and C0050 – Right Rear Wheel Speed Circuit Malfunction, are on the scan tool. There is damage to the front wheel speed sensor connector and harness connector and no apparent damage to the rear hub bearing. Replacing the hub bearings is a straightforward operation. The connector can be an integral part of the hub bearing or a connector wired to the bearing housing. The big question is what to do about the harness connector. What solutions are available? If a preassembled pigtail is available, the harness wires can be cut, spliced and sealed. Replace the harness connector, or hard wire the sensor. If a pigtail is not available, you can obtain connector parts from a number of sources. If parts are not available, the immediate solution would be to hard wire the front wheel sensor connector. If the connector is an integral part of the rear hub wheel bearing, hard wiring the connector is not a good idea.
FINDING THE RIGHT CONNECTOR
For undercar applications, there are many two-wire sealed connectors and, in some cases, two connectors are located in close proximity. To make sure a proper connection is made, the connectors are keyed and color-coded (Figure 1). To make a repair you have to have the right connector. Delphi and Deutsch catalog more than a thousand connectors that are supplied to the automotive industry. Delphi and Deutsch also supply connectors to the aftermarket. Finding the right connector can be a daunting task. Here is a sample of four Delphi connectors (Figure 2): From left to right, a GT Series 150; a 150 – 3.5 Centerline; Metri-Pack sealed 150.2 pull to seat; and a 150 push to seat. All four of these connectors can be used for sensor applications. They all have a terminal, cable seal(s), connector seal and device to assure that the terminal is locked into place. Where does that put you in the search for a connector? For most connector parts, the vehicle dealer is the most logical source. There are also suppliers in the aftermarket, such as Mouser Electronics, Terminal Supply and others, that have not been researched for this article. The Internet is a good place to look for an alternate source. Selected pigtail connector assemblies can be available from a vehicle dealer, ACDelco, Mopar or Motorcraft. If a pigtail is not available, you will have to source a connector, terminals and seals to fabricate your own pigtail. The problem is figuring out how to identify the connector by part number and how long will it take to get the parts. Connector part number and the pin out information can be found in service information that is obtainable from sources such as Alldata and Mitchell on Demand.
When terminals are mated, the integrity of the connection is dependent on the pressure generated by the spring element in the socket of the female terminal (Figure 3). Each time the connector is cycled (disconnected and connected), the spring element loses some of its tension. This translates into a resistance in the connection that can reduce the voltage and current flow for the terminals. Each cycle of the connector also presents an opportunity to damage a terminal. The result of the damage could cause an intermittent problem as the connection ages. In many cases, the replacement of a module or sensor resolves the intermittent problem, but the terminal responsible for the intermittent problem remains in the connector.
When the module is returned for warranty or as a core, it is given a functional test. In many cases, there is no trouble found in the module when the test is performed. To eliminate the connector as the source of the problem, you can check the terminals with a pull test. Use a new male with a wire attached and female terminal to establish a “feel” for tension required to pull the terminal from its socket, then test the terminals in the suspect connector (Figure 4). Replacement of a damaged terminal could be the solution to a nagging intermittent problem and the task of replacing a terminal in a connector can be as easy as fabricating a wire with a new terminal and seal.
When the terminal position device has been removed, you will need a pick to disengage the locking tab. The connector will have a slot for the pick. Once the tab is released, the terminal can be removed from the connector (Figure 5).
There is an old saying: “You are only as good as your tools.” The crimp for the terminal and seal should be made with a manufacturer’s recommended tool. The tool will have a set of dies that will attach the wire without the need to solder the connection. Figure 5 shows a good crimp. The terminal is seated by either pushing or pulling it into place. Each terminal will have a locking tab to secure it in the connector (Figure 3). The terminal position device will lock into place when the terminal is seated properly. A light coating of dielectric grease on the seals can make assembly easier and provide an extra barrier against moisture intrusion.
Whether you are able to get a preassembled pigtail or make your own, the most important part is making and sealing the splice to the harness. The splice has to be sealed to prevent moisture from corroding the connection. The best connection is non-insulated butt splice sealed with heat shrink tubing with an adhesive or hot melt liner. The splice should be positioned in a manner that will prevent any wire flex and the splice. A heat gun is the best tool for applying shrink tube to a splice (Figure 6).
Modules and connectors can only function as well as the wires and terminals that connect them. The next time you have an intermittent or module failure, check the connectors and the terminals for damage or a poor connection.
From the author: The reason for the use of the Delphi/Packard wiring and connectors is that my background and experience comes from GM as a service engineer.
An assortment of tools for fabricating connectors and wire splices (Figure 7). n