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2002 chevy trailblazer_lt_ext
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Discussion Starter · #1 ·
Ok started my truck today n went to get gas... Turned it off and went inside to pay... Started it again and light came on.. ok so i shut it off and started it again... Still... Seems to run fine... I do have a PCMforless tune but never get get the case re learn done... No one would do it in my area... Would that have anything to do with it?
 

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2003 chevy trailblazer_ls
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1,708 Posts
Dumb question but did you screw down the gas cap tight? If you did, go to autozone or some where and get the code read and bring the number back to us and lets see what we can do.
 

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2004 gmc
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The case relearn probably isn't the cause of the light, but you really, really need to get it done. Performance is suffering. I have a nearby independent GM mechanic with a tech tool that does it for $40. Don't just call dealers. SURELY there's somebody who can help. Don't just call it a CASE relearn - say you replaced your crankshaft sensor and need it recalibrated. Many folks don't know the phrase "CASE relearn". Are they saying they WON'T do it for you, or don't know what you're talking about? PCM4less knows what they're saying when they say you have to get it done.

On the SES light, can't do anything without the codes. Go get them read, then search here for that code. It's probably been discussed 42 times already.

If it HASN'T, then post up what the code is and we'll look in the shop manual for you.
 

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2005 chevy trailblazer_ls
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274 Posts
i just can't get anyone that will do it.... Will they charge me to get the codes read
Go to autozone and tell them that your SES light just came on. The scan is complementary (free). They will scan your vehicle and tell you the code(s) and will look it up for you for free to tell you what is wrong. Did you check the gas cap? take the cap off, and put it back on (make sure you get at-least a minimum of three good clicks). Hope this answers your question ;)
 

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2004 gmc
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Or you can buy a code reader, or go to a diagnostic center, or an independent mechanic who's experienced with new GM vehicles.

It's very difficult to understand there is NOBODY in your vicinity who can do a case relearn. Maybe you're not willing to pay a dealer? That's understandable, but the need for a case relearn is not a secret when you run a PCM swap with PCMforless. You need to budget for it before you get the tune, or else go with their loaner program so you get your original PCM back that doesn't need the relearn.

When you have a technologically advanced vehicle like a trailvoy, you either have to have a scan tool (or software and cable) to read codes, or find someone to do it for you, and except for places like Autozone, they will want to be paid for their time and for investing in the tool. There is no substitute for getting access to the codes when the SES light comes on.
 

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2005 chevy trailblazer_ls
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274 Posts
Or you can buy a code reader, or go to a diagnostic center, or an independent mechanic who's experienced with new GM vehicles.

It's very difficult to understand there is NOBODY in your vicinity who can do a case relearn. Maybe you're not willing to pay a dealer? That's understandable, but the need for a case relearn is not a secret when you run a PCM swap with PCMforless. You need to budget for it before you get the tune, or else go with their loaner program so you get your original PCM back that doesn't need the relearn.

When you have a technologically advanced vehicle like a trailvoy, you either have to have a scan tool (or software and cable) to read codes, or find someone to do it for you, and except for places like Autozone, they will want to be paid for their time and for investing in the tool. There is no substitute for getting access to the codes when the SES light comes on.
Best Bet Get A Scan Guage II :) I Love Mine :thumbsup:
 

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2002 chevy trailblazer_lt_ext
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Discussion Starter · #9 ·
The code that came up wuz P 0128 now i haven't had any overheating problems and it has been over 100 out here.... and the temp stays right at 210 going over alittle when sitting in traffic. Had the code erased and hasn't come back?
 

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2004 gmc
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P0128 could be caused by a bad sensor (which would show up in your gauge as a too-low reading - way under 210) or a sticking OPEN thermostat.

Maybe you had a one-time sticking open incident, and it might not do it again for a while. Just watch your gauge for being unexpectedly low after driving for any length of time.

How many miles, and have you ever changed the coolant?
 

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2003 chevy trailblazer_ls
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5,268 Posts
you have an 02-
nearing 100K.

the coolant is rated for 150,000 OR 5 yrs.
Its time you change the coolant.
While youre changing coolant- you may want to
change coolant
change thermostat
inspect upper and lower rad hoses
and
possibly change out the water pump and fan clutch- due to age...
This is if you dont want to drain an refill coolant several times within the next couple of years.
 

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2002 olds bravada
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2,369 Posts
you have an 02-
nearing 100K.

the coolant is rated for 150,000 OR 5 yrs.
Its time you change the coolant.
While youre changing coolant- you may want to
change coolant
change thermostat
inspect upper and lower rad hoses
and
possibly change out the water pump and fan clutch- due to age...
This is if you dont want to drain an refill coolant several times within the next couple of years.
I dont really think changing the fan clutch or waterpump is necessary unless you see signs of wear (fan wobbling, roaring, etc), its just a bit to costly. Although, I do recommend changing the hoses and thermostat as well as the coolant. :thumbsup:
 

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2005 chevy trailblazer_ls
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274 Posts
The code that came up wuz P 0128 now i haven't had any overheating problems and it has been over 100 out here.... and the temp stays right at 210 going over alittle when sitting in traffic. Had the code erased and hasn't come back?
You have: P0128 OBD-II Trouble Code
Technical Description

Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
What does that mean?

This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125

In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolant temperature (ECT) sensor reading, and the speed of the vehicle.

You will likely not notice any drivability problems other than the MIL illumination.
Causes

A code P0128 may mean that one or more of the following has happened:

* Low engine coolant level
* Leaking or stuck open thermostat
* Faulty cooling fan (running too much)
* Faulty coolant temperature (ECT) sensor
* Faulty intake air temperature (IAT) sensor

Possible Solutions

Past experience indicates that the most likely solution is to replace the thermostat. However here are some suggestions on troubleshooting and repairing a P0128 OBD-II code:

* Verify coolant strength & level
* Verify proper cooling fan operation (check if it's running more than it should). Replace if necessary.
* Verify proper engine coolant temperature (ECT) sensor operation, replace if necessary.
* Verify proper intake air temperature (IAT) sensor operation, replace if necessary.
* If the above items check out good, replace the thermostat

Good Luck :crazy:
 

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2003 gmc envoy_slt
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7,190 Posts
As stated, you may not notice any drive-ability problems, but you are wasting gas if it is running cold. Search for temp gauge. These gauges are more of an idiot light. It can read just under 210 but actually be down to 160 IIRC. It's good if you don't get the CEL anymore but keep a eye on the temp gauge.:m2:
 

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2002 olds bravada
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2,369 Posts
check your coolant level and the conditions of your hoses...
 
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