2000 Silverado 4wd light

I have a 2000 Silverado Ext Cab LS 5.3 4x4 z71 and the service 4wd light comes on the dash after driving about 3 miles or so. I took it to the dearlership today and had them run for errors and nothing came up. All of the push button dash lights are on and working. Any Ideas what could be causing this? Also I need to buy 2 cat converters for this truck and looking to find the correct ones without paying dealer prices. Thanks

really? all the diagnostic done by dealer and no ideas? :sarcasm1:

swap your automatic transfer switch. those are notorious to break down at about 60-70K miles. around 60 bucks and 5 minute job.

I have a 2000 Silverado Ext Cab LS 5.3 4x4 z71 and the service 4wd light comes on the dash after driving about 3 miles or so. I took it to the dearlership today and had them run for errors and nothing came up. All of the push button dash lights are on and working. Any Ideas what could be causing this? Also I need to buy 2 cat converters for this truck and looking to find the correct ones without paying dealer prices. Thanks


What is the mileage on it?
8 year or 80 K emmision warranty on cats.
What tarnsfer case?
Has transfer case ever been serviced?

If that is the best you dealer can do ask for your money back and find
Find another dealer or a good repair shopthat can find the problem?

Why does it need cats?

Dealer cats or a good parts house OEM type direct fit cat set up is the way to go but not cheap.

Make sure cats are bad and if they are find out what is causing them to go bad.

I have a 2000 Silverado Ext Cab LS 5.3 4x4 z71 and the service 4wd light comes on the dash after driving about 3 miles or so. I took it to the dearlership today and had them run for errors and nothing came up. All of the push button dash lights are on and working. Any Ideas what could be causing this? Also I need to buy 2 cat converters for this truck and looking to find the correct ones without paying dealer prices. Thanks

the 4wd dash select switch on my 2000 as well as many others ,, had bad solder joints on the switch pins/circuit board...I resoldered the pins after they were indeed poorly soldered....

this occured around the 40,ooomi point just after warrantee ran out...this should have been a recall...

same exact symptoms as you run a few miles and the 4wd lt is on..

when removing switch no tools required it is very easy,,,dealer will charge well over 100.oo to replace...

because this is intermittent the vehicle must not be shut down after the light comes on,,then the code should be there ...but the code will indicate a communication error...depending whats soldered bad...

the dealer could just shotgun this and charge you for componets not required...

truck has 135,000 miles on it. I have not serviced the transfer case in the 3 yrs I owned it. How do I know what one I have? I bought 2 quarts of the TRAC fluid from the dealership. The only reason thinking the Cats are bad is that the truck has lost power and piss pour gas milage 12-13mpg was at 18mpg when I purchased it. I have replaced everything I can think of like plugs, plug wires,air filer, all 4 o2 GM sensors, pressure regulator. EGT valve,fuel filter, I the clean mass air and throttle body bi-weekly. Today I went to a local mechanic (worked for GM dealership) that I have known for 35 years and he said he has had 3 trucks in the last 3 months with the same problem. Once he changed out the Cats they ran 100% better. But he wasn't sure why they were getting clogged. Any other Ideas?

truck has 135,000 miles on it. I have not serviced the transfer case in the 3 yrs I owned it. How do I know what one I have? I bought 2 quarts of the TRAC fluid from the dealership. The only reason thinking the Cats are bad is that the truck has lost power and piss pour gas milage 12-13mpg was at 18mpg when I purchased it. I have replaced everything I can think of like plugs, plug wires,air filer, all 4 o2 GM sensors, pressure regulator. EGT valve,fuel filter, I the clean mass air and throttle body bi-weekly. Today I went to a local mechanic (worked for GM dealership) that I have known for 35 years and he said he has had 3 trucks in the last 3 months with the same problem. Once he changed out the Cats they ran 100% better. But he wasn't sure why they were getting clogged. Any other Ideas?

Transfer case ID tag is on rear of transfer case.

On the cats proper testing before replacing.

What is engine vacuum at idle and at 2K rpm?

If cats are bad there is usuallay a reason for them going bad.

ahm, here's a novel idea:

did you try to read codes off ecm?

go to any Midas, get your truck up on the lift and they will blow 2 holes, one pre-cat and one post cat, to check on air flow. if it's same - your cat is still meowing fine. it's free of charge usually.

truck has 135,000 miles on it. I have not serviced the transfer case in the 3 yrs I owned it. How do I know what one I have? I bought 2 quarts of the TRAC fluid from the dealership. The only reason thinking the Cats are bad is that the truck has lost power and piss pour gas milage 12-13mpg was at 18mpg when I purchased it. I have replaced everything I can think of like plugs, plug wires,air filer, all 4 o2 GM sensors, pressure regulator. EGT valve,fuel filter, I the clean mass air and throttle body bi-weekly. Today I went to a local mechanic (worked for GM dealership) that I have known for 35 years and he said he has had 3 trucks in the last 3 months with the same problem. Once he changed out the Cats they ran 100% better. But he wasn't sure why they were getting clogged. Any other Ideas?

the cat restriction is a very real possible failure, with your lost power and MPG...checking for restriction should be done....before replacing...
the O2 sensors need replacing at the 100,ooomi point,,,these sensors the upstream ones can very well damage the cat.If not replaced at that mileage..also an intake manifold/antifreeze leak into the combustion chamber will damage the O2 and then the cats...

the muffler may also be restricted ....

when you install the trac II transfercase fluid you may need 2.25qts..and also need a pump that fits in a qt bottle..to fill..

always remove the top fill plug first ...use light torque to secure these plugs coat threads with thread sealant ,,just a light coating..this will ensure a good seal and removal ease...

the fluid removed should be a blue color ,,the darker the fluid the more you should consider a sooner replacement interval..

Mine did this also. Check the fluid level in the front differential. Top it up. Mine was down and this turned off the warning.

Jim

OK today took to a friend shop and did 4 hrs of diagnostics on the truck for the rough Idle, power loss and gas guzzling.

1- vacuum pressure.. 15-20 pressure
2- Cats check out fine...no back pressure.
3- fuel pressure...50-55 psi and idle and 45 psi when driving
4- scan for codes none
5- after idling 5 Min's with scanner in we had mis-fires on 3-5.
6- moved the coil packs around nothing changed.
7- idling it started to mis-fire on all cylinders with some cylinders as high as 3 times. like 3-5 then 1-8 ,2-6 , etc...
8- We think we narrowed it down to cam sensor or fuel pump but fuel pump seems to be working within the tolerances of the manual.

truck has 133,000 on it so I am gonna changed the fuel pump since it time for one and hope that cures it.
Has had injectors cleaned, plugs and wires, EGR valve, air cleaner, PCV, fuel filter done

Fuel pressure is to low .
Specs are 55/62.
You need to see 58-60 running on road.
Need engine vacuum reading at idle and at 2K rpm to rule out cat restriction.

Maf sensor or low fuel pressure will also cause missfire.

vacuum was 15 at idle and somewhere between 20-25. Can't remember what he said it went up to. I seen the needle move alot as soon as i took it to 2000rpm's. I couldn't clearly see gauge from my vantage point.

That is good.
On fuel pressure 5.3 have a lot of fuel pressure regulator problems.
If you replace the fuel fump go with a Delphi fuel fump.
Airtex and after market do not cut the mustard .
Good Luck

You fuel pressure is to low.
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.
MT

OK today took to a friend shop and did 4 hrs of diagnostics on the truck for the rough Idle, power loss and gas guzzling.

1- vacuum pressure.. 15-20 pressure
2- Cats check out fine...no back pressure.
3- fuel pressure...50-55 psi and idle and 45 psi when driving
4- scan for codes none
5- after idling 5 Min's with scanner in we had mis-fires on 3-5.
6- moved the coil packs around nothing changed.
7- idling it started to mis-fire on all cylinders with some cylinders as high as 3 times. like 3-5 then 1-8 ,2-6 , etc...
8- We think we narrowed it down to cam sensor or fuel pump but fuel pump seems to be working within the tolerances of the manual.

truck has 133,000 on it so I am gonna changed the fuel pump since it time for one and hope that cures it.
Has had injectors cleaned, plugs and wires, EGR valve, air cleaner, PCV, fuel filter done

the fuel pressure OEM GM spec min is 53psi.....60psi is good with new pump.... 53 psi and lower pump needs replacing or the ground at frame rail next to the fuel tank is not secure/clean or possible fuel pump relay...

lower fuel pressures cause random miss fires...as stated many times only use delphi pump....

I don't know what manual you refer to but this 2000 silverado requires the stated pressure ...........45 psi and it runs is surprising...

replace the relay/filter if you do have to replace the pump..

this engine has a cam and crank shaft sensor....these seldom have problems though some have had connector issues...

when we tested earlier today the fuel pressure did not drop when truck was shut off. It rose from 50 to 55 after a few mins. When you say to "replace the relay/filter" What do you mean by the relay? I only buy my parts from GM even though it costs me more now, but will not cost me twice as much to replace the cheap generic parts a year later.

when we tested earlier today the fuel pressure did not drop when truck was shut off. It rose from 50 to 55 after a few mins. When you say to "replace the relay/filter" What do you mean by the relay? I only buy my parts from GM even though it costs me more now, but will not cost me twice as much to replace the cheap generic parts a year later.

when the vehicle has this many miles and the fuel pump needs replacing the fuel pump relay should be replaced....the relay contacts may be worn,,,,if so this will damage the new pump...also the ground connection at the frame rail must be cleaned and secure..

if you use other non delphi pumps you will have problems.....all you have to do is read the many failures with these other junk pumps out there..on these forums...

your 45 psi / 50psi is saying the pump is N/G...

I own a 2000 silverado 5.3L 4X4 LT tow pkg....

Okay guys finally got the $$ to replace my fuel pump with GM parts. Easy job took only 40 mins to remove and install. We removed the bed with and electric engine hoist and was done in no time. But anyways replaced fuel pump still have the same problems. I still have misfires on 3-5 cylinders. then goes to random misfires.:banghead:

Okay guys finally got the $$ to replace my fuel pump with GM parts. Easy job took only 40 mins to remove and install. We removed the bed with and electric engine hoist and was done in no time. But anyways replaced fuel pump still have the same problems. I still have misfires on 3-5 cylinders. then goes to random misfires.:banghead:

Is the fuel pressure up to par now?
Lean fuel mix is a leading caude of missfires.
How is the MAF sensor?
Any aftermarket air intake stuff?
Any engine running codes beside missfire?

59psi at idle and 57 driving on the fuel pressure. MAF sensor cleaned with the appropriate cleaner and no broken wires or damage. Has stock air intake. Misfire codes it all I am getting. The misfires start after about 1 min or so.

59psi at idle and 57 driving on the fuel pressure. MAF sensor cleaned with the appropriate cleaner and no broken wires or damage. Has stock air intake. Misfire codes it all I am getting. The misfires start after about 1 min or so.

Does the scANNER SHOW WHICH CYLINER AND OR HOW MANY MISSFIRES FOR THAT CYLINDER?
Check for actual cylinder miss.
Plull plug wires off of plugs one at a time and check for good spark to plugs and make sure RPM drop on all cylinders is the same when wire pulled.

59psi at idle and 57 driving on the fuel pressure. MAF sensor cleaned with the appropriate cleaner and no broken wires or damage. Has stock air intake. Misfire codes it all I am getting. The misfires start after about 1 min or so.

with this engine the spark plug wires are easy to measure the resistance...this should be done ...the resistance should be 550 to 700 OHMS....

check plugs for damage and evidence of discoloration...
your fuel pressures are now in the normal range...did you replace the fuel filter "?? this is recommended at this time as well as the relay..

still it is very possible the intake is leaking....