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2003 chevy trailblazer_ls
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Discussion Starter · #1 ·
So, my first post.....

2003 Trailblazer. (NOT EXT)

So I have a host of issues..

1. P0128 - Thermostat issue, ordered a replacement.

2. Truck bounces 5 minutes after going over bumps, ordered new Reflex Struts (front), Sensa-trac (Rears)

3. Whining like a hoot owl from the A/C clutch bearing, ordered one.

4. Periodically speedometer stops working; doesn't register correct speed, and slowly ticks back when stopping, ordered new speed sensor.

5. 4WD selector switch blinks and goes dark when going from AWD to 2WD to 4WD, replaced the switch, works MOST of the time now, with some intermittent NOT. What to do?

6. Sometimes when I first start up the truck, it sounds like a F16, and at the same time the first (2) low fan speeds of A/C don't work. After a few minutes (usually), I gain the 2 low fan speeds again, and all I hear is the damned A/C clutch bearing, and not the F16. Assuming it is the fan clutch, ordered a new Dorman from Rockauto to replace. CORRECT?

7. Just replaced the blower resistor.

8. MPG in the toilet, down around 16 or so, and very sluggish...throttle body need cleaning? Does fan clutch play into that?

So you see, we have some issues to resolve. So being that I am going to have to tear into her, and given that she has 92K miles, are there other ISSUES I should address or can do to resolve some things and make her last a while longer. What other preventative things should I look at servicing while torn apart?

Please help!
 

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2004 gmc
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Did you just buy this, or did it deteriorate while you've had it?

Anyway, speedometer is more likely to be a cheap stepper motor in the gauge cluster - available on Ebay.

4WD (my specialty system). You should try exercising it a lot, and listen for the two different motor sounds underneath. The front axle actuator is a high pitched whine that only makes noise on the 2WD->A4WD transition and vice versa. The transfer case encoder motor is a lower pitched (larger motor) that makes a noise on every mode transition. If one of these motors is failing to report its position accurately back to the transfer case control module (TCCM) that could cause the failures. You can do this in neutral with the engine off, to better listen to the noises. Try it a bunch and see if you can hear anything different happening if it fails. Keep good observation skills for the conditions of any failure you see, and then post up about it.

Did replacing the resistor pack get your fan speeds all back?

At that mileage, the TB definitely needs cleaning.

http://forums.trailvoy.com/articles.php?do=viewarticle&artid=91

The transfer case fluid NEEDS to be changed every 50K.

I would do the plugs and look closely at the anti-sway bar end links - a reported weak point.
 

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2003 trailblazer_lt
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What other preventative things should I look at servicing while torn apart?
Well Im really close to the big 100K, and have been preparing to do the following (the ones in bold are recommended per maintainence schedule):

Replace plugs
Air filter
Fuel filter
Clean t-body
Change the transfer case fluid
Change the trans fluid and filter


Although there is no recommended diff fluid interval, I will be doing them too.

Since you will be doing the T-stat the coolant will be changed.

Also, #4 sounds more like a stepper motor problem as opposed to a VSS. Others may agree. Or not.
 

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Discussion Starter · #4 ·
And another.....

When replacing the struts, do I also need to replace the strut mounts, or leave them alone?

The changing of the resistor did get 2 fan speeds back, but when the fan clutch turns my truck into an F16, I lose em again for a while.
 

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2004 gmc
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The strut mounts are probably OK. You have to bang around pretty hard offroad to stress them into shearing. Heat may deteriorate the rubber, though. Look closely at them. Also start spraying PB Blaster around a few days before beginning that sort of work, to reduce frustration.

Never heard of a connection between the fan clutch and HVAC blower fan speeds. The schematic suggests nothing.
 

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2003 gmc envoy_slt
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Once the t-stat is changed, your mileage should improve. The t-stat is a PITA to replace, so put the new one in water with a thermometer to make sure it opens at the right temp.:m2:
 
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