'03 Sierra ABS sensor

aziemba

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#1
2003 GMC Sierra/4.8L V8/ 95,000 miles
While applying the brake at low speed the ABS activates causing the pedal to shudder. I was told this was a TSB and that the ABS sensors should be cleaned which will take care of this issue. I removed the hex nut holding the front ABS sensor in place, but was unable to pull it out to clean it.
Any help would be appreciated.
Thank You ???
 
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#2
It should come out.

What codes are you getting?
 
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#3
If its stuck really tight I sometimes use a little bit of penetrating oil.

Ford_Dude
 

aziemba

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#4
I am getting codes
P0445 and P0559 All evap canister items.
Truck is having difficulty starting takes two to three turns of the key to start the truck. ???
 
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#5
On the starting.
Check fuel pressure up to par and leak down and fuel pressure regulator for fuel in vacuum line.
On ABS problem.
You need to get it on a ABS capable scanner to check ABS system and get codes.
Post back any ABS codes you have.
Crunch
 

aziemba

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#6
OK Guys,
I committed the biggest sin ever and went to the dealer with the truck. (A personal no no for me) and they found the following codes.
For the starting issue codes P0449 and P0455
For the brake system Code P0559

Their diagnosis:
ABS issue is result of Passenger side hub bearing requires replacement due to bearing and speed sensor faulty. $510.32 +tax

Starting problem is a result of fuel pump requiring replacement. $795.49+tax
Although they did tell me they found a loose emissions wire that they reconnected and the engine light turned off.

and then they added the following

Fuel filter $69.95
Fuel Injection Flush $129.95
Emissions Service $115.95

for a grand total of $1621.66

None the less I will be replacing the hub myself for a part cost of $115.00
I know I can get a pump for $250 but am not sure I should undertake that task...
and am taking my truck to my local mechanic for fuel pump repair if that is really the problem.
What do you guys think do these fixes seem right?? ??? :( :eek: :eek: :eek:
 
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#7
You should have went to your local mechaic to start with. :ROFL
And saveed that high dollar dealer code read out.
If your are going to fix it.
Go with the codes and see where they lead you.
On the fuel pump test the pressure and if it needs fuel pump go with the AC/delphi fuel pump.
After market and airtex fuel fumps are junk.

Check fuel pressure guide lines.
Specs on it is 55/62 lbs of pressure
Here is some guide lines of fuel pressure checking.

Hard to start cold.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
Later V6 and V8 gm engines should have 55-66 fuel pressure.
Cold start should be 55/62 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 55/62 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak.
If pressure does not come up with return line pinched or blocked off.
Go to fuel filter and hook a gauge direct to a line at fuel filter.
Pressure should come up to 75 or more and will hold after fuel pump is turned off.
If it leaks down there after fuel pump is turned off it is LEAKING BACK THREW PUMP CHECK VALVE OR PUMP MODULE LINES.
Post back your fuel pressure readings.
Crunch
Good Luck
 

aziemba

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#8
Thanks for the input.
I'll be working on the truck this weekend.
Anyone know what size wrench is required to remove the fuel filter. I am having a heck of a time finding a wrench that will fit the nut on the filter itself.
Thanks Again ;)
 

aziemba

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#9
OKAY
I replaced the fuel filter today and the front passenger hub.
Truck now starts on second turn of key instead of third or fourth.

ABS situation is all set with new hub in place. fixed

One down one to go!! :eek:
 

aziemba

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#10
Took the truck to my local mechanic and he verified what I thought that the fuel pump does not need replacement.
He was stumped though and said that there are a number of TSB's for this truck.
He said it could be a computer issue, but was not sure.
Basically said that either I take it to another dealer or live with it.
I will keep troubleshooting though.
Truck starts on second try now and when warmed up starts on first try.

I don't know anyone have any comments on this one. ???

Where can I get a list of the TSB's for this vehicle.
 
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#11
The all data online sub.
Will have them and keep you up to date with all new ones.
Also will tell you how to fix it.
Upper right top of this web page.

http://www.alldata.com/products/diy/index.html