Auto Service World
Feature   June 1, 2004   by CARS Magazine


More fuel tank safety and GM ABS brakes...

More fuel tank safety and GM ABS brakes

Two great tips and how municipal governments are destroying our industry.

This month SSGM received more feedback about safety in the shop and odd intermittents in GM light truck ABS. Regular reader Mike Duguay has a safety tip for techs working with fuel tanks.

Hi Jim:

I thought that I would send you a few comments that you might wish to enter as “Letters to the Editor”.

1st…As a result of Jon Pysh’s story (December 2003 issue), I have been promoting the idea of technicians taking the extra step of grounding the vehicle while it is sitting on the hoist, to ensure that any POTENTIAL static electricity is removed. Here’s why…About one year after Jon’s accident, I was removing a fuel tank on a 1996 Caravan. I was using a battery “jumper-cable” which was clamped to the hoist while the other end was secured to the frame of the van. Just before I disconnected the filler tube (hose) from the tank, so as to facilitate draining it, I decided to “touch” the jumper-cable clamp, and was surprised by the SHOCK THAT I RECEIVED! I stopped what I was doing, and put a static strap onto my wrist before completing the removal of the tank.

I get various comments from technicians, ranging from “That’s a good point”, to “The vehicle is grounded while its on the hoist…so why worry about it”? My reply? …Take my personal experience…. Place it in your memory… whistle while your walking past the graveyard…and hope it never happens to you!

2nd…”Where Have All The ‘Small’ Shops Gone”? Try as hard as you can to find an automotive shop at the local gas bar. (You’ll quickly be frustrated…. Why? ) The various Municipal councils have been forcing independent small automotive shops to all be located in one location (area). Their rationale seems to be based on the following: “If we keep them all in one area, we can minimize the impact that these shops will have on the environment! After all, the waste – oil, antifreeze, and various chemicals that these businesses produce, should be contained (restricted if you prefer) to one location!” OK, I can understand their concerns, but by passing such laws (zoning restrictions), the city “fathers” are creating other problems:

Economic hardship for the shop owners and Environmental problems for their respective municipalities.

“Economic Hardship”… How is this happening? Think about this: It’s hard enough to keep a small business profitable even when the shop is the ONLY AUTOMOTIVE SHOP in an area. Now, force the business into an industrial complex, and place SIX – TO – TEN other automotive shops in the SAME AREA, and what is the result? Profitability goes into the toilet! The customer now “nickel and dimes” you to death and to keep him, your bottom-line is sacrificed (at least cut into)!

Here is another thing to think about…. Why don’t the “City Fathers” treat other businesses the SAME WAY they treat the automotive shops? For example, let’s force all the hair salons (barber shops), and lawyers and even the grocery stores into ONE location! This way, the public could instantly compare prices, and shop accordingly! (Wow, what a concept!)

“Environmental Problems”…The very thing that such by-laws are SUPPOSED to solve is in fact backfiring! How so? …Lets go back in time for a moment…. When I was a teenager, I worked at a local gas station that also included a repair shop. When problems occurred to my father’s car, he would drive it to the local shop, and then walk back home! The gas station was ONLY FOUR BLOCKS from our home.

I recently visited the area after all these years and found that the closest repair shop, is now OVER FIFTEEN BLOCKS AWAY! How does this effect the environment?

Consider if the vehicle is experiencing an emission – related problem (i.e.: misfiring), instead of driving FOUR blocks, now the customer is driving a GREATER DISTANCE and emitting MORE pollutants into the atmosphere! And nine-out-of-ten times, the technician / owner will drive the customer home in his / her OWN vehicle, thus ADDING to the environmental problem. Don’t most city councils wave the “Let’s Protect The Environment Banner”? The reader can draw his own conclusions.

Mike Duguay

Injectronics Training

Surrey, B.C.

Al Schott, from David Chevrolet in St. Catherines, Ontario, has identified a possible cause for the GM light truck ABS issues reported by several readers. This one is worth thinking about when you’re at the wheel end of any GM light truck.

Dear Jim:

Just a thought on your Chevy 4×4 ABS issues. I have seen several cases where the ABS will activate at low speeds on a normal stop. This of course gives the driver the feeling of little or no stopping power. In my experience the major contributor to this condition is rust build-up where the front ABS sensors are attached to the hub and bearing assembly. The rust builds between the surface of the hub and the sensor and actually lifts the sensor enough to change the air gap between the sensor and reluctor. This weakens the a.c. voltage produced by that sensor and at low speeds causes the brake control module to interpret it as a sudden drop in wheel speed as if the brake had locked that wheel. Of course a bad wheel bearing could have the same effect.

In most cases, if the bearings are good, it is a simple matter of removing the sensor from the hub and cleaning the mounting surface. I recommend doing both sides at the same time to ensure both sensor readings are the same. It is also a good idea to coat that sensor mounting surface with a good rust paint to stop it from happening again.

Al Schott

David Chevrolet

St. Catharines, Ont.