Intermittents and Poor Connections

INTERMITTENT AND POOR CONNECTIONS
Most intermittents are caused by faulty electrical connections or wiring. Some items to check are:
^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out).

^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact.

^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector.

^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to "Checking Terminal Contact" in this section for the specific procedure.

^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter ensures that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to "Checking Terminal Contact" in this section for specifics.

^ Poor terminal-to-wire connection. Checking this requires removing the terminal from the connector body. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc.

^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle.

^ Wiring broken inside the insulation. This condition could cause a continuity check or voltage check to show a good circuit, but if only 1 or 2 strands of the multi-strand-type wire are intact, the system may not operate properly. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair.

Checking Terminal Contact
When diagnosing an electrical system that uses Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit J 38125-A instruction manual J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component.

Frequently, a diagnostic chart leads to a step that reads "Check for proper connection...." Mating terminals must be inspected to ensure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation.

Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or an intermittently open circuit.

Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang (see Figure 1), can result in poor terminal contact causing an open or intermittently open circuit.

Follow the procedure below to check terminal contact.
1. Separate the connector halves. Refer to Terminal Repair Kit J 38125-A instruction manual J 38125-4.

2. Inspect the connector halves for contamination. Contamination results in a white or green buildup within the connector body or between terminals, causing high terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body.

3. Using an equivalent male terminal from the Terminal Repair Kit J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact requires a certain amount of force to separate the terminals.

4. Using an equivalent female terminal from the Terminal Repair Kit J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question, using a terminal from the Terminal Repair Kit J 38125-A.

If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a DVM connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit.