2002 LW300 Brake Boost Failure?

[rfisher]

hi pierrot - used to be the same way with cussing . didnt want the church ladies to hear my adjectives and oaths. then i found out church ladies cuss just as badly. so i relearned how to cuss. since you have given me good advice on this forum, i volunteer to give you a refresher course in advanced cussing. wonder if my brake booster will last until 200k. 188k right now. thanks tons bob f

[fdryer]

Brian90638, click on each snapshot to open a new page for a larger view. A Hall effect sensor is magnetic pickup device to detect metal passing by similar to the crank sensor detecting teeth on crankshafts to generate signals. The metal particles probably aren't enough to corrupt signal generation. The flow chart spells out some simple troubleshooting steps to determine if the sensor is faulty or intermittent.

Snapshots from my '03 L200/L300 manuals. I presume P0343 is a general error code, applicable to all Saturn models. The wiring and flow chart details are specific to L300/LW300 models, presuming they share the same engine and sensor configuration.

[Brian90638]

Originally Posted by fdryer

Ugh,....... I'll get back to you after I drag out 50 lbs of service manuals and find P0343. I prefer to reply from an authoritative point of view holding a service manual as my reference. I trip on them all the time. It was wonderful when free access to an electronic library was available from a few clicks away on a mouse.

I'm sure you're a busy man fdryer and I hate bothering you. Did you happen to locate a possible cause?

[fdryer]

No bother at all. I'm not sure why P0343 continues to pop up and a reason to post service manual descriptions and procedures to determine which way to proceed. The troubleshooting flow chart is very good although anytime the word scantool is included, it means GMs Tech II scantool, not everyone's personal reader. Some imagination is needed to read between the lines when a scantool is needed for say, missing cam position counts.

If this were my problem, I'd use a multimeter to measure for 5v between pins 1 and 3 on the cam sensor connections. If possible, removing the cam sensor and reconnecting it then measuring pin 2 for analog signals (any voltage output) while waving a screwdriver tip past the sensor should display something. A multimeter with a bar graph will show instantaneous signal output faster than the digital display. Testing cam sensor output is rudimentary but may reveal whether or not its outputting when metal is waved past it. Measuring for resistance of the sensor between pins may help too. There shouldn't be any short between pins.

The flow chart goes into more details to follow up, before or after measuring sensor supplied voltage and output. This presumes wiring is intact otherwise continuity testing of wiring may be necessary. Examining the ecm dual plugs for loose connections may help since all sensors receive and send signals to it.

[pierrot]

Originally Posted by rfisher

...since you have given me good advice on this forum,

I'm happy that you've found something useful in my comments here in SaturnFans. Thank you!

Originally Posted by rfisher

i volunteer to give you a refresher course in advanced cussing. wonder if my brake booster will last until 200k. 188k right now.

A course in advanced cussing, eh? Well, I suppose that I'll pass even though it is a kind offer. My youth pastor whom I really liked and respected (when I was 14), and who continues to have my respect long after, told us that if we couldn't think of something other than a "curse" word to use then we didn't have much of an imagination. He was right about that. I do find it more satisfying to fool people into thinking I'm about to blurt out something really bad only and then take it into something they didn't expect and which was not in the cussing world.

Regardless, as it relates to the power brake booster it's one of the least likely items to ever fail on an automobile. I'm reasonably certain the booster in your car will go for many years to come.

[rfisher]

hello my good compadre and sage advisor pierrot- as a masta cussa who has trained many, keep in mind that cussing is a very creative activity especially because it clears your sinuses allowing more oxygen to get to your cerebrum making you momentarily smarter. this in turn increases the likelihood of figuring out complicated mechanical repairs to jalopies and washing machines . never underestimate its power. good point about brake boosters. old rule from workng on 60s and 70s cars was if brake pedal got much harder to push to stop it was a tipoff to a shot leaking booster. with the booster stinko you had to use more pressure to stop car since the springs in the system were heavier and stiffer with power braking. my 01 L100 has drum rears and disc fronts. can remember only working on two in 60 years. cant be repaired, have to replace. hope mine passes 200k and still stops the car. looked at the diagram and doubt the control valve in the vacuum line from the manifold is available if that craps out. keep up the good work. bob f

[pierrot]

Originally Posted by rfisher

...old rule from workng on 60s and 70s cars was if brake pedal got much harder to push to stop it was a tipoff to a shot leaking booster. with the booster stinko you had to use more pressure to stop car since the springs in the system were heavier and stiffer with power braking.

Yes, you're exactly correct. I learned of this once when a booster was to be replaced at my father's service station. I was warned that the amount of pressure to depress the brake pedal would be much greater than that needed on a non-boosted brake system and it was true. In fact, the pressure was greater than I'd imagined it would be.

Originally Posted by rfisher

my 01 L100 has drum rears and disc fronts. can remember only working on two in 60 years. cant be repaired, have to replace. hope mine passes 200k and still stops the car. looked at the diagram and doubt the control valve in the vacuum line from the manifold is available if that craps out.

My car also came with front disc/rear drums. (I converted the rear drums to disc in 2016, and I like the change! ) The power brake check valve is no longer available as a new OE part. I broke my check valve some time last year and glued it back together so that it worked, but it was an ugly repair. I went to a wrecking yard to pick up a complete hose and check valve assembly. Of course, it works.

[rfisher]

hi pierrot- my friend you better be careful about doing an ugly repair appearance on a car. that will seem bohemian enough to deny your admission to your hometowns yacht and country club, but no worries merely driving an ancient model T( aka saturn model L) . the car alone would stop your membership. me? has happened the same way many times even though i slightly improved my language. havent seen that vacuum valve anywhere in the aftermarket either. luckily it hasnt blown yet. have almost given up finding rear coil springs too. luckily they too havent busted yet. did you know power brakes do not stop a car any faster than non power- just easier on the foot pressure. stopping distance is more a function of weight, momentum and tire adhesion. uncle moe used to say, brakes wont stop the car , they stop the wheels. told moe about force vectors and coefficients of friction. you dont want to know how he characterized what i said. feelings were again hurt. thanks tons bob f