Injector Terminal Fretting -- The Invisible Menace

The Mystery
Over 1000 Multec 2 injectors are returned through the warranty system every year (fig. 1). Every returned injector is put through a series of functional tests to identify electrical faults, injector leaks and incorrect injector flows.

Once a cause for failure is identified, the information is used to take corrective action: improved manufacturing procedures, design or materials enhancements, or improved service procedures.

About 60% of returned injectors pass all of the functional tests. Some operate with no apparent failures when put on test vehicles in an effort to reproduce the complaint. These injectors are called No Trouble Found (NTF) injectors.
Over half of the vehicles which had NTF injectors replaced never returned to the dealer for a similar complaint. The mystery is: how did the replacement of what appears to be a good injector solve a driveability problem?

The Investigation
An in-depth review of repair orders and warranty claims found that DTCs P0300 and P0200 were the common link with injector replacements. These clues triggered an investigation into the integrity of the Multec 2 electrical connector. Technicians who carefully document DTCs and diagnostic test results provide valuable information for these types of investigations.

The Invisible Menace Found
Because the female injector connector is rarely replaced, the study focused on the injectors’ electrical terminal pins. To gain access to the terminal pins, the surrounding plastic had to be cut away. The terminal pins were examined with a high power microscope to see if there were any indications of connection problems.

A thin layer of oxide was found to be forming on the injector male pin terminal at the point where it contacts the female harness connection. Invisible to the naked eye, “fretting corrosion” was found on a majority of the NTF injector terminals (fig. 2).

“Fretting” describes a tiny rubbing motion that occurs between two surfaces (usually on the order of 10-100 microns). “Fretting corrosion” refers to a build up of insulating, oxidized debris that forms on electrical connections due to a fretting action at the contact points. Injector vibration, engine vibration, and electrical harness movement are contributors to the fretting motion.

Refer to the accompanying illustrations (fig. 3).

Step 1 shows the tin oxide layer with clean tin-on-tin contact, resulting in a stable connection.

Steps 2 and 3 show further progression of fretting corrosion (formation of oxide layer).

Step 4 shows the contact point after numerous fretting cycles, resulting in an unstable electrical connection.

The amount of oxide build-up determines how drastic the effect will be on the injector circuit. Worst case is a total loss of continuity in the connection resulting in P0200 (Injector Circuit Fault) and P0300 (Misfire) codes being set. If the oxides create a high resistance circuit, insufficient current will be available to properly open the injector, resulting in unstable fuel delivery and ultimately a P0300 DTC. High resistance in the circuit will not necessarily set a DTC P0200.

Keep in mind that a connection with fretting corrosion is unstable. Because movement causes fretting, any vibration may create a condition where the connection varies from an open circuit, to a high resistance connection, to a good connection.

What To Do?
Disconnecting and reconnecting the injector connector will temporarily scrape the oxides off, creating a good connection. This explains why replacing a suspected faulty injector with a new injector appears to repair the condition. But, if the conditions still exist for fretting to occur, it will eventually come back.

Using lubricant part number 12377900 (in Canada, 10953529) to coat the terminals is the best preventative measure to take. This provides a lubricant for the terminals as well as providing an oxygen barrier to guard against oxide formation.

To apply the lubricant, gather a small amount (about the size of a BB) on the end of your finger (fig. 4). Press it into the end of the disconnected female connector, making sure to cover both cavities (fig. 5). Reconnecting the harness connection onto the injector will wipe the lubricant onto the male terminal pins.

- Thanks to Randy Pearl and Dave Sant

figure 2

figure 3  

In the past, your dealership has received an allotment of printed service bulletins on a regular basis, in the Dealer World Delivery box. In addition, many dealerships also subscribe to receive additional copies to distribute to technicians. At the same time, service bulletins have also been viewable on the Service Information (SI) website.

TIP: If you still do not have ID and password to access SI, contact your Area Service Manager or call the Techline Customer Support Center at 800.828.6860.

By the end of June, 2003, there will be a change in the way printed bulletins are distributed. Printed bulletins will no longer be sent automatically to your dealership. You can continue receiving printed bulletins, at the price of 10c per copy. Your service manager has received a Dealer World subscription form on which to place your order. The subscription will continue on a regular basis until you choose to change it.

Whether your dealership chooses to subscribe to receive printed bulletins or not, here’s how to find bulletins on SI.

- Go to the website at http://service.gm.com.
- Click on Service Information.

- Put in your ID and password.

- Click on Number Search if you know the number of the bulletin.

- Click on Latest News if you want to read a list of the most recent bulletins issued (past 8 weeks). These are organized by Bulletins, Campaigns and Preliminary Information. Within categories, the information is organized by typical SI topics, such as Engine, Steering, HVAC and so on.

- Click on the Y+P+K button if you want to see bulletins that pertain to a specific year, platform and keyword.

Some printed material will continue to come, whether you subscribe to printed bulletins or not.

1. Warranty Administration bulletins and Advanced Service Information bulletins will continue to be distributed in printed form for the foreseeable future.

2. Your dealership will receive a printed summary of bulletins issued, every two weeks. This parallels the information on the Latest News page of the website.

3. And finally, your dealership will receive a blue-bannered printed bulletin called the Field Product Reminder, every two weeks. This will contain a list of “Fix It Right The First Time” items for cars and trucks. This list is also being repeated on the rear cover of TechLink each month.

TIP: You may want to remind owners that they can subscribe to receive service bulletins as well. Every owner’s manual contains the necessary ordering information.l.

- Thanks to Alan Srodawa and Frank Flees

A/C Refrigerant System Sealer and Leak Detection Guidelines

Refer to bulletin 03-01-38-001 for details. Here are the highlights.

Various A/C system sealers, stop-leak, and seal conditioners are available to consumers and to the A/C repair industry. Because they are easily obtained, there’s a likelihood that you will encounter a vehicle with an A/C system contaminated by one of these products.

TIP: A GE-47548 Sealant Detector is now available from Kent-Moore. It is discussed in an accompanying article.

Products Not Endorsed
GM Service Operations does not endorse or approve use of such products in any GM vehicle. These products may damage A/C systems and service equipment.

IMPORTANT: A/C systems contaminated with sealers, stop-leak, or seal conditioners are not covered by GM New Vehicle Warranty or Replacement Part Warranty.

A typical stop-leak sealant is carried through the A/C system in the refrigerant oil. If a leak occurs, some of the sealant passes out of the refrigerant system into the atmosphere. It cures in the presence of moisture, which is supposed to “seal” the leak. If there is moisture in the vehicle’s A/C system, or in the plumbing of your A/C service equipment, the stop-leak can cure there, causing circulation problems.

In addition to stop-leak products, there is another family of products which is not recommended or endorsed. These are the seal conditioners, which cause system o-rings and other rubber components to swell to stop leaks.

These seal swellers cannot be detected using the GE-47548 Sealant Detector or any other known tool at this time. Seal swellers can cause similar problems once added to A/C systems. The sealer swellers also pose a potential threat to recover/scavenger units, because they contain rubber o-rings and other parts.

The Approved Approach
Various federal, state/provincial and local regulations prohibit recharging an A/C system with known leaks. In support of these regulations, GM Service Operations recommends using recommended leak detection devices to locate leaks, and then using recommended procedures to repair or replace leaking components.

Flushing
Using GM-approved (refrigerant-based) system flushing on a contaminated system can introduce these contaminants into the A/C service equipment, which may cause equipment damage.

It may be necessary to replace all components affected by the additives to correct a contaminated system.

- Thanks to Dave Roland

Owners of 1999-2003 Chevrolet Silverado and GMC Sierra may comment that a door sags or is hard to open or close.

A door hinge pin and bushing kit is available from:

Ken-Co Industries LTD
Burlington, Ontario, Canada
phone 1.800.263.4283
fax 1.905.335.1829
email info@ken-co.com
attention Ken Spragg
website www.ken-co.com

Each door requires 2 kits. The minimum order is 6 kits.

A kit includes 2 brass bushings (fig. 8), 2 zinc coated hinge pins (fig. 9), 2 nyloc locknuts, 1 washer, and instructions.

Using the kit (fig. 10) permits repairing and realigning the door without having to cut off the hinge, and no painting is required.

- Thanks to Steve Love

Battery Green Eye Eliminated

In the next few months, you will begin seeing new vehicles equipped with Delphi batteries that no longer have the “green eye” (built-in hydrometer).

This is a rolling change which will eventually include all GM cars and trucks. Service replacement batteries will be “eyeless” as well, as current stock is depleted and replaced.

TIP: The green eye was never installed in the AGM battery, used in Corvettes and the 2004 Pontiac Grand Prix, because these batteries do not contain free liquid to operate the hydrometer.

State of Charge
You are of course familiar with the intended use for the green eye -- indicating the battery’s state of charge. This information is useful in determining whether a battery is charged, needs to be charged, or lacks sufficient electrolyte to permit charging.

The green eye information is largely redundant now that the Midtronics J-42000-U conductance tester is in widespread use. This tester can analyze a battery with a low state of charge, so long as it has sufficient voltage to operate the tester.

There is another diagnostic test you can perform to determine the battery’s state of charge, the Open Circuit Voltage (OCV) test.

Open Circuit Voltage Test
OCV may be used to estimate the state of charge. This method is generally accurate +/- 10%. Temperature also affects OCV, so that must be taken into account.

The voltmeter you use must be properly calibrated, capable of reading to the nearest 0.01 volt, and accurate within +/- 0.005 volt.

The battery must be free of all current flow (that’s why it’s called open circuit) -- it’s best to disconnect it entirely.

A battery becomes unstable for a period of time after it is charged or discharged. So, it’s important to know what has happened to battery before performing the OCV test.

If the battery has not been charged or discharged within 12 hours -- the OCV is fairly stable and the test can be performed using the OCV vs % Charge table.

If the battery has been charged, discharged or used in a vehicle within 12 hours -- the OCV may not be stable enough for a reliable reading. If the battery has been charged, you must first remove any surface charge using a carbon pile. Discharge the battery at 300 amperes for 15 seconds. Disconnect the pile, allow 15 seconds for recovery, then read the OCV.

If the battery has only been discharged, just wait at least 15 seconds for the voltage to stabilize after disconnecting the load before testing.
A battery with a 65% or greater state of charge is generally considered charged enough to be returned to normal service.

TIP: If the battery will be used in slow traffic, short trips, or very hot or cold weather, it should be at least 90% full charge before returning to service.

If Charging is Required
The new “eyeless” batteries now include the battery’s amp-hour (AH) rating on the label. This information can be useful in setting up your battery charger. The AH rating was not previously available for GM OE batteries.

TIP: Most battery replacement guides in the US will still be based on the OE battery’s CCA and RC (Reserve Capacity) ratings. Don’t confuse the RC and AH ratings when selecting a replacement battery model – they are different tests.

- Thanks tozz

This information will help you understand the J-38125-C Terminal Repair Kit and use it more effectively (fig. 11).

Some definitions:
An electrical terminal is the formed metal attached to the end of a wire to provide electrical connection with another wire or with a component.

Groups of terminals are organized into molded plastic blocks called connectors.

Groups of wires, with their terminals and connectors, are gathered into wiring harnesses.

Differences Between Production and Service Terminals
Service terminals are not necessarily the same as production terminals. A single service terminal may replace several production terminal numbers.

Service terminals are chosen so the crimp wings fit the crimp tools in the J-38125-C. You should use the crimp matrix in the Terminal Repair Kit Instruction Book for best results.

Service terminals may have more tin or gold content then the production terminal.

Service terminals may have a higher contact force than the production terminal. In the assembly plant, where actions are repetitive, connector assembly effort is an issue that does not come up in service.

Where Do Service Terminals Come From?
Service terminals are NOT available from GMSPO. A parts bulletin IB03-044 has been issued to this effect.

All service terminals should be ordered from SPX (Kent-Moore) at 1.800.345.2233.

All components and tools of the J-38125-C Terminal Repair Kit should be ordered from SPX (Kent-Moore) at 1.800.345.2233.

It will be important to keep the complete J-38125-C Terminal Repair Kit in proper order and stocked with terminals and tools, as more wiring suppliers make their appearance in GM vehicles.

What’s the Distinction Between Wiring Harness Suppliers and Connection System Suppliers?
Wiring harness suppliers build harnesses according to engineering specifications. This means that a wiring harness supplier will use their own connection system, plus those from other suppliers, so most harnesses contain an assortment of connection systems.

This is a list of connection system suppliers used by GM. Some of these companies are also wiring harness suppliers.
- AFL/EPC
- Bosch
- Cinch
- Delphi
- FCI
- JAE
- JST
- Koste
- Molex
- Sumitomo
- Tyco/AMP
- Yazaki

There is an effort in engineering to limit the proliferation of connection system suppliers.

How Are All These Terminals Organized in the J-38125-C Terminal Repair Kit?
There are five Wiring Suppliers for GM Power and Signal Distribution (PASD) systems:
- AFL
- Delphi
- Lear
- Sumitomo
- Yazaki

These five supply the wiring used in North American-engineered platforms.

TIP: Some platforms are not engineered in North America. These include the International Joint Venture Vehicle Platforms (IJVP): Vibe, Tracker, Isuzu-supplied MD trucks, and vehicles with pre-wired Honda engines. Service terminals for these are not included in the J-38125-C Terminal Repair Kit.

The J-38125-C Terminal Repair Kit was originally a Delphi terminal repair kit only. Now we have Delphi trays, Lear trays, Sumitomo trays and Yazaki trays, with AFL to be added.

Trays are named for the five wiring harness manufacturers. If a harness manufacturer also makes terminals, their terminals are in their trays. Terminals from other terminal manufacturers may also be included in the harness makers’ trays.

AFL/EPC is the wiring supplier for the ‘04 Corvette, and two other future programs. An AFL tray will be added to the Terminal Repair Kit in the near future and any AFL terminals used for the first time in the ‘04 Corvette will be in that tray.

Delphi is the wiring supplier for every truck platform except the M/L Van. Delphi is also the wiring supplier for most car platforms. Delphi has the most history with GM and has the most trays in the Terminal Repair Kit. Delphi trays may also contain service terminals from:
- Delphi
- Bosch
- FCI
- JAE
- JST
- Molex

Lear is the wiring supplier for the M/L Van, and the Saturn Vue and Ion. Lear makes no terminals or connection systems. Instead, they use terminals from other suppliers. Lear trays contain service terminals from:
- Bosch
- Molex
- Tyco/AMP

TIP: Tyco/AMP terminals used by all wiring harness suppliers, so a Tyco/AMP terminal may be in any tray.

Sumitomo is the wiring supplier for a future truck program. Sumitomo makes terminals and connection systems. The Sumitomo tray will be filled in the near future.

Yazaki is the wiring supplier for the Cadillac CTS, the ‘04 Cadillac SRX and a future Cadillac program. Yazaki also makes terminals and connection systems. There are 5 trays of Yazaki service terminals. The Cadillac CTS was first to use these terminals. Yazaki trays contain service terminals from:
- Yazaki
- Kostel
- Molex
- Tyco/AMP

How Do You Know Whose Terminal You’re Looking At?
You can get your clue from the connector from which it was removed. Look on the connector for these identifying symbols. Many are small or difficult to find.

Connector Symbols

All suppliers use their own connection systems when they can, but most will have a high Delphi connector content, because GM still uses a high number of Delphi components.

What’s Coming?
A Federal Agency called USCAR sets test and footprint standards for all US vehicle manufacturers. The effort to comply with USCAR will be seen in all GM vehicles. This will ultimately result in connection systems that will have the same look and feel, regardless of the supplier (fig. 12). There is even an effort to have a GM-common terminal in several popular sizes, which will greatly reduce the increasing number of service terminals we now see in the J-38125-C Terminal Repair Kit.

Information included in SI is also being revised. A pilot for a new connector end view is planed for the ‘04 Cadillac XLR service information (fig. 13). This connector end view will give you the service terminal number that is in the J-38125-C Terminal Repair Kit.

TIP: Because service terminals are not stocked in GMSPO, service terminals have supplier part numbers. The new connector end view will for the first time give you the real connector or pigtail part number, which is stocked in GMSPO. This connector end view may take some time to make its appearance in all the service information but every effort is being made to do so.

A Word About Pigtails
A pigtail consists of a connector with terminals and short lengths of wire already installed. They are available for numerous electrical devices (up to 8 cavities), and are intended to be spliced in place of a damaged connector.

Pigtails are sold through the AC Delco side of GMSPO. A GM Dealer parts department can find a pigtail by application (2003 Cavalier generator, for instance) but not by description (4-way female Metri-Pack 150 series).

AC Delco Catalog 16A-200 has a complete list and pictures of pigtails. Call 1.800.ACDELCO (1.800.461.8606 in Canada) to find your local AC Delco Parts distributor, who can assist you in obtaining a catalog. There is also an AC Delco web site www.acdelco.com with online catalog that will help, not only for pigtails but also for other items.

- Thanks to John Roberts

Oil Life System Reset Procedures -- Trucks

Many GM cars and trucks are equipped with an oil life system which determines when an oil change is required. After the oil has been changed, it’s necessary to reset the system.

Procedures for resetting 2001 through 2004 trucks are published here. Passenger cars were published last month.

The information for this article is the same as you will find in the applicable owner or service manual.

To find this information in SI:

- Select the vehicle
- Select category General Information
- Select category Maintenance and Lubrication
- Select category Maintenance and then GM Oil Life System-Resetting.

You may be able to use the Search function using the words Oil Life System Resetting.

2001 - 04 Aztek
2002 - 04 Rendezvous
If the vehicle does not have the optional Driver Information Center (DIC) do the following:
1. With the ignition key in ON but the engine off, fully push and release the accelerator pedal slowly three times within five seconds.

2. Turn the key to OFF.

3. If the CHANGE ENGINE OIL message comes back on, the engine oil life monitor has not reset. Repeat the procedure.

If the vehicle has the optional DIC, do the following:
1. Turn the ignition to ON with the engine off.

2. Press the MODE button until the DIC reads OIL LIFE LEFT/HOLD SET TO RESET.

3. Press and hold the SET button until 100% is displayed.

You will hear three chimes and the CHANGE ENGINE OIL message will go off. If the CHANGE ENGINE OIL message comes back on, the monitor has not reset. Repeat the procedure.

2001 - 04 Montana
2001 - 04 Silhouette
2001 - 04 Venture
1. With the ignition key in RUN but the engine off, repeatedly push the trip/reset button until OIL is displayed on the Driver Information Center.

2. Once OIL is displayed, push and hold the trip/reset button for five seconds. The number will disappear and be replaced by 100 (indicating 100% oil life remaining).

3. Turn the key to OFF.

4. If the change engine oil message comes back on, the engine oil life monitor has not reset. Repeat the procedure.

2002 - 04 Bravada
2002 - 04 TrailBlazer
2002 - 04 Envoy
2004 Ranier w/o DIC
1. Turn the ignition key to RUN with the engine off.

2. Fully press and release the accelerator pedal three times within five seconds.

3. If the CHANGE ENG OIL light flashes for five seconds, the system is reset. If the light does not flash, repeat the procedure.

2004 Ranier with DIC
1. Press the fuel information button until ENGINE OIL LIFE appears in the display.

2. To reset the monitor, press and hold the select button while ENGINE OIL LIFE is displayed.

2004 Canyon
2004 Colorado
1. Display ENGINE OIL LIFE on the DIC.

2. Press and hold the select button. The oil life will change to 100%.

3. Turn the key to OFF.

If the CHANGE/OIL message comes back on when you start the vehicle, the engine oil life system has not reset. Repeat the procedure.

2004 SSR with DIC
1. Press the fuel information button until ENGINE OIL LIFE appears in the display.

2. To reset the Oil Life System, press and hold the select button while ENGINE OIL LIFE is displayed.

2001 - 04 Sierra
2002 - 04 Sierra Denali
2001 - 04 Silverado
2001 - 04 Yukon and Yukon XL
2001 - 04 Tahoe and Suburban
2001 - 04 Escalade
2002 - 04 Escalade EXT
2002 - 04 Avalanche
2001 - 04 Yukon Denali
2003 - 04 Hummer H2
2003 - 04 Express
2003 - 04 Savana
1. Turn the ignition to RUN but with the engine off.

2. Fully push and release the accelerator pedal slowly three times within five seconds.

3. If the Change Oil Soon light flashes, the system is resetting.

4. Turn the key to OFF.

5. Start the vehicle.

6. The oil life will change to 100%.

7. If the Change Oil Soon light comes back on, the system has not reset.

Repeat the procedure.

2001 - 04 B7 Chassis Medium Duty
1. Turn the ignition to START but with the engine off.

2. Fully press and release the accelerator pedal three times within 10 seconds.

3. If the CHANGE OIL light flashes for five seconds, the system is reset.

4. If the light does not display for five seconds, you will need to reset the system again.

2003 - 04 560 C-Series
1. Turn the ignition to RUN but with the engine off.

2. Fully press and release the accelerator pedal three times within 10 seconds.

3. If the CHANGE OIL light flashes for five seconds, the system is reset.

4. If the light does not display for five seconds, you will need to reset the system again.

- Thanks to Jerry Garfield

return to Table of Contents

Owners of some 2003 S-10 and Sonoma Crew Cab models may comment that a high pitch squeak can be heard outside and underneath the rear of vehicle when driving over bumps. The park brake cable may contact the mounting bracket. To correct the condition, secure the park brake cable away from the mounting bracket.

- Thanks to GM Technical Assistance

Truck Issues – Fix It Right The First Time

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