O'Great LC/LX gurus... Braking system issue on 98' LX

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Nov 1, 2015
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Magnolia, TX
Jumped into the LX this afternoon, started normally, but the ABS and Battery lights were lit. I stepped on the brake and it goes to the floor without any real resistance. I hear the ABS pump running though...

My rig has about 140k on the ODO which puts it in range of other LC/LX with ABS / Brake issues. Was wondering if this sounds like just a master cylinder rebuild given the ABS pump seems to be running or if I am in for the big enchilada? Either way I want to make sure that I am not just putting a bandaid on a bigger problem.

Thanks for your advice.

PS. I ran a search but did not find a similar issue with the ABS + Battery light. Also noticed the Battery / charge gauge was peaked abnormally high. The battery is ~~4 mo old.

My rig is a converted soccer mom-mobile so no major off roading (yet), rust, or other issues - its actually pretty clean in the engine bay and everywhere else.
 
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OK, looking at my problem more objectively and tying in the high volt meter reading (approaching 18v) could this just be a wonky alternator?
 

Skidoo

 
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does not sound like MC, have you checked brake lines for leaks? Whats your fluid level.
Just turning key on without starting does pedal go to floor?
 
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does not sound like MC, have you checked brake lines for leaks? Whats your fluid level.
Just turning key on without starting does pedal go to floor?
No leaks, fluid level at the full/max level marking on the tank and when turing on the key the pedal does not go to the floor with out pressing it. I can hear the ABS pump run but the battery light comes on first and then when actuating the pedal the ABS light comes on. If i stab the pedal quickly the brake light will also illuminate for a brief second. Given the high voltage reading I am seeing on the dash volt meter I am wondering if this is a voltage regulator (alternator) issue which is cascading to other systems causing them to go into alert / protective mode... The voltage is reading abnormally high close to 18v.
 
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I would test the battery voltage at the battery itself, if you are getting over voltage then I would address this first by changing the voltage regulator or alternator if you cannot get the regulator as a separate item. The abs does monitor battery voltage and bring up fault codes so there is a link between the two. Over voltage can damage sensitive components so getting this solved would be a priority, do your standard checks of main earths and fuses and double check your battery after as that might be toast also.
 

PADDO

 
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^ I like where you're going with this and strongly agree that if IG1 and or IG2 is indeed 18v then that must be rectified (no pun) as it will cause codes and potential damage. However, at least in the '03+, if you don't have an in range IG1 or IG2 voltage (serpentine belt off for example) that'll throw codes and set ABS lights and buzzers too.
 
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2001LC

 
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I'm no expert but can't see why high voltage on dash indicator would make a difference. The voltage reading may be normally during warm up as battery will draining a bit from parasitic and starting draws.

Try turning key to on without starting, you'll hear pump. You stated fluid level is at max, as you hear pump motor watch fluid level it should draw down during this time.

Now without pressing brake pedal and key off level should be low. With key off pump brake pedal 40 time, reservoir level will come up to max as booster empties and pedal stroke lengthens. Then turning key on pump should run 30 to 40 sec, and brake fluid level drop.

FSM
Low pedal or spongy:
  1. Fluid leak
  2. Air in brake systems.
  3. Piston seals (worn or damaged)
  4. Hydraulic brake booster (faulty)
 
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It will bring up fault codes and buzzers but you could test the pedal action when the voltage is in a more normal range, it isn't a fix just a test, I would rather have under voltage than over voltage when trying things out. My logic is that you don't lose your brakes or that the pedal goes to the floor when you lose your alternator.

Reply to PADDO
 
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I'm no expert but can't see why high voltage on dash indicator would make a difference. The voltage reading may be normally during warm up as battery will draining a bit from parasitic and starting draws.

Try turning key to on without starting, you'll hear pump. You stated fluid level is at max, as you hear pump motor watch fluid level it should draw down during this time.

Now without pressing brake pedal and key off level should be low. With key off pump brake pedal 40 time, reservoir level will come up to max as booster empties and pedal stroke lengthens. Then turning key on pump should run 30 to 40 sec, and brake fluid level drop.

FSM
Low pedal or spongy:
  1. Fluid leak
  2. Air in brake systems.
  3. Piston seals (worn or damaged)
  4. Hydraulic brake booster (faulty)
I think the voltage could be a link as before I start my engine my brake pedal is to the floor, then it builds up when engine is started. So some process in the abs or braking system does this, the abs is sensitive to voltage issues so could be corrupted or damaged through voltage problems.
 

2001LC

 
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I think the voltage could be a link as before I start my engine my brake pedal is to the floor, then it builds up when engine is started. So some process in the abs or braking system does this, the abs is sensitive to voltage issues so could be corrupted or damaged through voltage problems.
Not starting, but only turning key on voltage will not be issue during above test.

No leaks, fluid level at the full/max level marking on the tank and when turing on the key the pedal does not go to the floor with out pressing it.
Level should not be at max until pedal depressed 40 times, so booster may be empting (not normal).
I read this as pedal goes to floor when he presses when key on. (not normal)

I'm not consider dash lights at this point, only OP's above statement.
 

PADDO

 
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It will bring up fault codes and buzzers but you could test the pedal action when the voltage is in a more normal range, it isn't a fix just a test, I would rather have under voltage than over voltage when trying things out. My logic is that you don't lose your brakes or that the pedal goes to the floor when you lose your alternator.

Reply to PADDO
Agreed, I was attempting to point out that not having IG will set codes, lights and buzzers in conjunction with the existing fault(s) - potentially masking the root cause. Time for OP to read codes and pull out the DI flow charts.
image.png
 
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Not starting, but only turning key on voltage will not be issue during above test.


Level should not be at max until pedal depressed 40 times, so booster may be empting (not normal).
I read this as pedal goes to floor when he presses when key on. (not normal)

I'm not consider dash lights at this point, only OP's above statement.
The point I am trying to make is if the OP does have a over voltage problem then that would be my first priority, there is a link between the two faults as voltage does affect abs. It may not be the only issue but it could be the cause, as over voltage damages electrical components. You don't want to be replacing parts when the over voltage is still present as the new parts could end up in the bin also. Just be cautious.

Agree with PADDO that to get the fault codes now before proceeding.
 
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I think the voltage could be a link as before I start my engine my brake pedal is to the floor, then it builds up when engine is started. So some process in the abs or braking system does this, the abs is sensitive to voltage issues so could be corrupted or damaged through voltage problems.
Pedal is in the normal position but resistance / pressure does not seem to be building per usual. Given the seeming electrical connection to this I think I am going to replace the alternator and go from there --> In hind sight I should have done this when I did my TB service a few weeks ago. :-(
 
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Alternator replaced voltage back to normal, no more trouble lights and brake pressure is also back to normal.

Removing the alternator requires some patience as you twist and contort it out, much like that Russian gymnast you used to date. Also it did require that I loosen the steering pump and slide it forward about 1/2" altogether it's probably a 1 1/2 Banana job.
 
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