Hib Halverson
Technical Writer for Internet & Print Media
I have a pal who's a dealer and every once in a while, I stop in for coffee and donuts and, sometimes I get a look at recent TSBs.
By law, TSBs are public information. Now, the car companies, General Motors included, make TSBs a little hard to get, in that you have to get the bulletin number from NHTSA then order the bulletin by number from Helm Inc, GM's service data publisher, but lay-persons and DIYs can get TSBs. More detailed info on how to do that is in your owner's manual.
GM issues hundreds of service bulletins each year. Considering all the cars it makes world-wide and that the subjects of these bulletins range from pretty inane to very important, hundreds per year really isn't abnormal. There were two issued in the last 4-6 weeks that are worthy of note by C5 Corvette owners.
The first, relates to problems GM has documented with, strangely enough, aftermarket alarm systems and catalytic convertors.
Aftermarket alarms--and when I say "alarms," I mean just that and not vehicle locater systems such as LoJack--are unnecessary, considering the sophisticated security system already on today's Corvette. Nevertheless, dealers and alarm vendors convince many people that they need aftermarket alarms with the myth they offer a level of protection above what already exists on that car. Alarms that produce eight different sirens, screeches and yowls in rotation or tell anyone standing within 50 ft. of the car to "Step away from the vehicle," in reality, offer no more security than the car already has, and in many cases, provide less protection because they are poorly engineered or poorly installed.
It's the cheap installation that's the issue, here. The majority of alarm vendors pay their installers little more than a Burger King wage yet these installers are expected to have a level of understanding of Corvette electrical system that rivals the skills of experienced electrical system technicians. That may be the expectation, but it is seldom the reality.
After 1995, Corvettes are equipped with OBD2 exhaust emissions controls which include misfire detection systems. With OBD2 disgnostics, GM and all the car companies discovered that these misfire detection systems were sensitive to a lot of new problems relating to aftermarket electrical component compatibility. Many of these aftermarket components were seldom problematic prior to OBD2. That brings us to Technical Service Bulletin #02-06-05-004: "Misfire DTCs and Catalytic Converter Damage Due to Installation of Alarm Systems." This TSB affects all 97-03 Corvettes and most all other GM light vehicles.
GM engineers, trying to figure-out the causes of catalytic converter damage, have concluded that improperly installed aftermarket alarm systems can cause misfire codes and damage to the converters. The alarms in-question use a circuit interrupt that works on the car's ignition circuit. These alarms, also, use relays and normal vehicle movement can trigger these relays to engage and disengage the ignition circuit while the vehicle is in motion. These disruptions, which may last only a few milliseconds, may cause more fuel flow to be commanded by the PCM. Over time, this periodic extra fuel can cause the misfire codes and ultimately damage the converter assembly due to overly rich mixture.
GM could not identify any alarms that utilize solid-state circuitry that would eliminate this concern. Because of this, GM recommends all alarm systems be wired through the starter circuit in order to avoid this problem. Dealers have been made aware of this issue and have been advised to note the alarm wiring on vehicles with aftermarket alarm systems that come in for repair, particularly repairs of catalytic converter damage that seems not to have a known cause. Keep in mind, if a dealer determines a cat failure is due to the owner's installaton of an alarm system, GM can rightly deny warranty coverage for the cat failure. When you find out what new cats cost, trust me....you'll never buy another aftermarket alarm again.
Bottom line: if you insist on a (for the most-part vaueless) aftermarket alarm system, for the good of your C5's cats; make sure that alarm is wired through the starter circuit. If the alarm installer says it can't be done that way, don't buy the alarm.
The second TSB is potentially a more serious issue. Apparently, GM has a new problem with some Gen 3 engines and that brings us to TSB #02-06-01-029: "Needle Bearings Found In Oil Pan (Replace Rocker Arms)". Currently, this affects 1998-2002 Corvettes, along with a number of other GM vehicles using the Gen 3 small-block V8 engine family.
You or a service technician may find needle bearings in the drain oil during an engine oil change. These needles may be found in either the drain screen, the drain pan or on the magnetic drain plug.
If you do your own oil changes and you find needles in your drain oil, most likely one or more of the engine's roller rocker arms have failed. If you find needles and the car is under warranty, STOP![i/] Save the evidence, then take the car to a dealer for warranty repair. Make sure you show the dealer the needles you found in the oil and tell the dealer you are aware of this bulletin. The dealer should replace all 16 rockers and pull the oil pan for cleaning.
If the car is out of warranty and you're doing the work yourself, pull the rocker covers and inspect all 16 rockers for bearing retainer cap failure. If you find a bad rocker, inspect no farther. Replace all 16 rockers with PN 10214664 then pull the oil pan and clean it out. If no rocker arm problem is found, do not change the rockers. Check the car's service records for a previous rocker repair. If a repair was done before, the engine might not have been properly cleaned of loose needles. Remove the oil pan and clean out any additional needles you find.
Directions on how to do all this work is in the factory service manual.
If you don't do your own work, the next time you take the car into your dealer or other service vendor for an oil change, advise the service facility of this bulletin and ask them to, specifically, check the drain oil for needles.
By law, TSBs are public information. Now, the car companies, General Motors included, make TSBs a little hard to get, in that you have to get the bulletin number from NHTSA then order the bulletin by number from Helm Inc, GM's service data publisher, but lay-persons and DIYs can get TSBs. More detailed info on how to do that is in your owner's manual.
GM issues hundreds of service bulletins each year. Considering all the cars it makes world-wide and that the subjects of these bulletins range from pretty inane to very important, hundreds per year really isn't abnormal. There were two issued in the last 4-6 weeks that are worthy of note by C5 Corvette owners.
The first, relates to problems GM has documented with, strangely enough, aftermarket alarm systems and catalytic convertors.
Aftermarket alarms--and when I say "alarms," I mean just that and not vehicle locater systems such as LoJack--are unnecessary, considering the sophisticated security system already on today's Corvette. Nevertheless, dealers and alarm vendors convince many people that they need aftermarket alarms with the myth they offer a level of protection above what already exists on that car. Alarms that produce eight different sirens, screeches and yowls in rotation or tell anyone standing within 50 ft. of the car to "Step away from the vehicle," in reality, offer no more security than the car already has, and in many cases, provide less protection because they are poorly engineered or poorly installed.
It's the cheap installation that's the issue, here. The majority of alarm vendors pay their installers little more than a Burger King wage yet these installers are expected to have a level of understanding of Corvette electrical system that rivals the skills of experienced electrical system technicians. That may be the expectation, but it is seldom the reality.
After 1995, Corvettes are equipped with OBD2 exhaust emissions controls which include misfire detection systems. With OBD2 disgnostics, GM and all the car companies discovered that these misfire detection systems were sensitive to a lot of new problems relating to aftermarket electrical component compatibility. Many of these aftermarket components were seldom problematic prior to OBD2. That brings us to Technical Service Bulletin #02-06-05-004: "Misfire DTCs and Catalytic Converter Damage Due to Installation of Alarm Systems." This TSB affects all 97-03 Corvettes and most all other GM light vehicles.
GM engineers, trying to figure-out the causes of catalytic converter damage, have concluded that improperly installed aftermarket alarm systems can cause misfire codes and damage to the converters. The alarms in-question use a circuit interrupt that works on the car's ignition circuit. These alarms, also, use relays and normal vehicle movement can trigger these relays to engage and disengage the ignition circuit while the vehicle is in motion. These disruptions, which may last only a few milliseconds, may cause more fuel flow to be commanded by the PCM. Over time, this periodic extra fuel can cause the misfire codes and ultimately damage the converter assembly due to overly rich mixture.
GM could not identify any alarms that utilize solid-state circuitry that would eliminate this concern. Because of this, GM recommends all alarm systems be wired through the starter circuit in order to avoid this problem. Dealers have been made aware of this issue and have been advised to note the alarm wiring on vehicles with aftermarket alarm systems that come in for repair, particularly repairs of catalytic converter damage that seems not to have a known cause. Keep in mind, if a dealer determines a cat failure is due to the owner's installaton of an alarm system, GM can rightly deny warranty coverage for the cat failure. When you find out what new cats cost, trust me....you'll never buy another aftermarket alarm again.
Bottom line: if you insist on a (for the most-part vaueless) aftermarket alarm system, for the good of your C5's cats; make sure that alarm is wired through the starter circuit. If the alarm installer says it can't be done that way, don't buy the alarm.
The second TSB is potentially a more serious issue. Apparently, GM has a new problem with some Gen 3 engines and that brings us to TSB #02-06-01-029: "Needle Bearings Found In Oil Pan (Replace Rocker Arms)". Currently, this affects 1998-2002 Corvettes, along with a number of other GM vehicles using the Gen 3 small-block V8 engine family.
You or a service technician may find needle bearings in the drain oil during an engine oil change. These needles may be found in either the drain screen, the drain pan or on the magnetic drain plug.
If you do your own oil changes and you find needles in your drain oil, most likely one or more of the engine's roller rocker arms have failed. If you find needles and the car is under warranty, STOP![i/] Save the evidence, then take the car to a dealer for warranty repair. Make sure you show the dealer the needles you found in the oil and tell the dealer you are aware of this bulletin. The dealer should replace all 16 rockers and pull the oil pan for cleaning.
If the car is out of warranty and you're doing the work yourself, pull the rocker covers and inspect all 16 rockers for bearing retainer cap failure. If you find a bad rocker, inspect no farther. Replace all 16 rockers with PN 10214664 then pull the oil pan and clean it out. If no rocker arm problem is found, do not change the rockers. Check the car's service records for a previous rocker repair. If a repair was done before, the engine might not have been properly cleaned of loose needles. Remove the oil pan and clean out any additional needles you find.
Directions on how to do all this work is in the factory service manual.
If you don't do your own work, the next time you take the car into your dealer or other service vendor for an oil change, advise the service facility of this bulletin and ask them to, specifically, check the drain oil for needles.
