Need help with CEL code

[johnsoax]

I just got back from Autozone, where they told me that my Check Engine Light code was P0128 - Which is something like tempurature cooler than called for. So my car is running colder than it should. They suggested that I change the Thermistat. It's only $9 so that isn't a problem. I just wanted to run it by you guys first and see what you thought?

[bud_one]

The DTC P0128 Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature diagnostic monitors the relationship between engine temperature and engine running time. The ECT sensor input is used to monitor the performance of the engine cooling system thermostat. A DTC P0128 may set if the ECT sensor voltage does not indicate that the engine coolant temperature has increased sufficiently during running of the diagnostic. When the ambient air temperature and engine operating conditions are right, the powertrain control module (PCM) starts the diagnostic using a water temperature counter. The water temperature counter times how long the cooling system takes to reach 75°C (167°F). Failure to reach 75°C (167°F) within the diagnostic window can indicate a malfunctioning thermostat.Conditions for Running the DTC • The engine coolant temperature (ECT) is between 10°C (50°F) and 20°C (68°F). • The intake air temperature (IAT) is between -9 to +36°C (14-97°F). • DTC P0128 runs once per drive cycle when the above conditions have been met.Conditions for Setting the DTCThe engine coolant temperature failed to reach at least 75°C (167°F) during the running of the water temperature counter diagnostic.Action Taken When the DTC Sets • The PCM illuminates the malfunction indicator lamp (MIL). • The PCM records the operating conditions at the time the diagnostic fails. This information is stored in the Freeze Frame buffer.Conditions for Clearing the MIL/DTC • The MIL turns OFF after 3 consecutively passing trips without a fault present. • A History DTC clears after 40 consecutive warm-up cycles without a fault. • Use the scan tool Clear DTC Information function.Diagnostic AidsCheck for the following conditions: • A faulty thermostat that stays open slightly can cause DTC P0128 to set in cold weather when the vehicle is started and allowed to sit while warming up. Replace any suspect thermostat. Refer to Thermostat Diagnosis in Engine Cooling. • An incorrect thermostat can cause the engine to warm up slowly. Replace any thermostat that does not meet OEM specifications. Refer to Thermostat Diagnosis in Engine Cooling. • Use the Temperature vs Resistance table in order to evaluate the possibility of a shifted ECT sensor. A shifted sensor could result in DTC P0128. Refer to Temperature vs Resistance . • Check for the proper operation of the engine cooling system, including the correct coolant level. • Check for a faulty electrical connection to the PCM.If DTC P0128 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining the vehicle operating conditions when the DTC was first set.Test DescriptionThe numbers below refer to the step numbers on the diagnostic table. 1. The Diagnostic System Check-Engine Controls prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference. 2. This step compares the ECT temperature to the IAT temperature. This inspection is to be performed when the vehicle has reached ambient room temperature. At that time both the surrounding air temperature and the engine coolant temperature are nearly equal. If the ECT sensor and circuit are OK, both sensors should indicate the same temperature. 3. This step checks that the temperature of the engine coolant increases at least 20°C (36°F) within 10 minutes. If the temperature does not increase at least 20°C (38°F) there is a fault with the ECT sensor or the engine cooling system. 4. Fault not present indicates the condition that caused DTC P0128 to set is intermittent and not currently present. If no other DTCs are stored, refer to Diagnostic Aids for additional information on diagnosing an intermittent DTC P0128.Hope this helps....

[joatmon]

The matrix manual says for a P0128, first check the cooling fan, then the thermostat. I guess if the cooling fan runs all the time it might keep the engine from warming up.

[Mavrik]

Quote, originally posted by joatmon »The matrix manual says for a P0128, first check the cooling fan, then the thermostat. I guess if the cooling fan runs all the time it might keep the engine from warming up. I agree, in the cases where I came across that code, it was a stat or the fan. In some cases both but those were rare.

[johnsoax]

Well, it went away again. So if it comes back, I am going to replace the thermistat.Thanks for all the help guys

[johnsoax]

OK, I bought a new thermistate, and I can't find the one in the car .Someone with a service manual, HELP. I followed the top radiator line to the engine, but couldn't find where the thermistate is.

[joatmon]

the thermostat is at the engine end of the lower radiator hose, up in there behind the alternator. The manual indicates that the the thermostat has some sort of air bleed valve, and that this should be within 10° of vertical, facing up when installed

[johnsoax]

Thank you. When I get a chance, I will see if it is there. I guess that means I have to drain the coolant system. I was hoping to not have to do that.

[joatmon]

hopefully it will be clean, so you can catch and re-use the coolantprobably help to take off the alternator to get better access to the thermostat housing

[johnsoax]

It should be clean, I just had the system flushed and cleaned 15k miles ago.

[johnsoax]

Any tips on how to safely drain the coolant? And containers to put it in?I also noticed Monday that my coolant was low. I would think this would make the car run too hot, not too cold.Thanks

[johnsoax]

Well, it went away all summer, but now is back. I am going to change the thing soon. I have never messed with belts. If I remove the alternator, will I have to re-tighten the belts?

[joatmon]

There is a belt tensioner, a spring loaded pulley that keeps the belt tight. On other cars I have had, the alternator pivoted and you had to pull it hard and then tighten it in place to keep the belt tight, this car is different from that. There is no pivot in the alternator mount, it is not used as a belt tensioner.There is a pic of the belt routing pattern here somewhere, I think it also shows what part to move to let up tension on the belt, then you could just slip it off the alternator.sucks that the CEL is back

[johnsoax]

Well, I screwed up. I couldn't figure out how to get the plugs off the alternator (still can't), and somehow blew the 100A "fuse" in the engine compartment fuse block, but I can't get the thing out of the block. Anyone have any ideas?Yes, I forgot to unhook the ground, I was just looking this morning before I headed out to get any parts I needed. Crap, I should have just let the dealer do it.

[joatmon]

I just looked at mine, and it looks like it should just pull out, but I tried on my car and I am unable to get it out. Maybe when you get the new one there will be a clue if there is anything special about it.

[johnsoax]

You have to unbolt it. I had to take the battery and the airbox out so that I could flip over the fuse box and unbolt it. By the way, the bolts are two different sizes (go figure) I will attach some pictures this evening. I'm off to autozone to buy the part (hopefully they have it).Anyone have an idea how to unplug the alternator? I also need to pick up a 19mm wrench as my 19mm 1/2 drive won't fit, and my 3/8" drive doesn't give me ANY leverage at all.

[joatmon]

it looks liek there are three connectors, one looks like it just pulls off, the second looks like it has a tab you have to (edit)pry up slightly(/edit) to release the connector, and the third, the main power connector has a plastic cover on that doesn't immediately pop off, I assume it pries off to reveal a stud/nut/terminal. how much was a 100A fuse?

[johnsoax]

Quote, originally posted by joatmon »it looks liek there are three connectors, one looks like it just pulls off, the second looks like it has a tab you have to (edit)pry up slightly(/edit) to release the connector, and the third, the main power connector has a plastic cover on that doesn't immediately pop off, I assume it pries off to reveal a stud/nut/terminal. how much was a 100A fuse?It was $2.49.You have to take off the entire bottom of the fuse block, which means that you have to take out the battery, and the air box. I have it all working again. BUT, I haven't even gotten to what I started out with, because I don't have any tool that can reach the stupid 19mm nut for the tensioner. My 1/2" Rachet doesn't fit, and neither does the breaking bar I picked up at Autozone. But my 3/8" Rachet does fit, but I have no leverage to move it.

[johnsoax]

Ok, I have some pictures for you. This one is right after I got the stupid fuse out.

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[johnsoax]

This one is of the bolt hole in the side of the fuse block

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[johnsoax]

This is the part. I had to put it back together, as I told you when I pulled it out at first, it didn't come out in one piece .

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[johnsoax]

And here is everything almost put back together.

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[johnsoax]

Ok, Finally going to attempt the Stat change this weekend . I know, I have been saying that for months.

[johnsoax]

Does anyone have the proceedure for removing the Alternator? I will be digging into this this weekend, and won't have a spare car to get any parts if something goes wrong.

[johnsoax]

Quote, originally posted by johnsoax »Does anyone have the proceedure for removing the Alternator? I will be digging into this this weekend, and won't have a spare car to get any parts if something goes wrong.Anybody? Can't figure out how to unplug these plugs

[johnsoax]

Please, please, please can some one post the section on how to remove the alternator???? It is 1 degree here and my poor vibe never heats up .

[joatmon]

here is the only info I have on it, the full procedure, and will look at my car tonight to see if I can get a better pic of the actual unit.

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[joatmon]

Quote, originally posted by johnsoax »Anybody? Can't figure out how to unplug these plugsThere are three connectors.NOTE: Disconnect the negative battery terminal first to prevent shorting out that big fuse againThe first is the main 12V output. It has a rigid plastic cover that you can pry off relatively easily. Underneasth there is a stud with a 10 mm nut holding the wire.

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[joatmon]

The second is a standard connector type on these cars. You have to squeeze the tab on the end of the connector, (push the end of the tab in) and the flap will pivot and release it's grip, have to do this as you pull the connector off.

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[joatmon]

The third connector is the ground, this one is different. There is a tab on the connector, but instead of squeezing it to release, like on connector two above, you have to lift the tab away from the connector body somewhat. I used a small screwdriver to pry the tab a little bit and then could slide the connector off the alternator. Space conspires to make that difficult if you've got big hands Looks like that terminal on my alternator is starting to get some corrosion, guess I'll have to add cleaning that up to my todo list.EDIT - I wonder if that is an actual connector, or just a wire clamp.

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[johnsoax]

THANKS!!!!!!!!!!!!!!!!!!!You have been a great help. Could I ask for one more favor? Could I also have page 14-4?Thanks.

[Baltovibe]

Quote, originally posted by johnsoax »Could I also have page 14-4?Obtained from http://forums.genvibe.com/zerothread?id=1156

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[Baltovibe]

Oops ... noticed you have a GT. Page 14-177 might be more applicable.

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[Baltovibe]

and ...

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[johnsoax]

Quote, originally posted by Baltovibe »Obtained from http://forums.genvibe.com/zerothread?id=1156Thanks a bunch guys. I can't believe that I didn't find that link earlier.

[joatmon]

Quote, originally posted by Baltovibe »Oops ... noticed you have a GT. Page 14-177 might be more applicable.and remember, no loud swearing or other extra noise, it is important to "fix it quietly"

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[johnsoax]

Quote, originally posted by joatmon »and remember, no loud swearing or other extra noise, it is important to "fix it quietly" I saw that too. Hopefully I will start on this tonight, but as it is only 7 degrees outside and I don't have a heated garage, I may not.

[johnsoax]

Thanks for all the help. Started the work about about 7:15 (CST) and finished with everything, including cleaning up and test drive about 10 minutes ago.Must sleep Got the main drive belt changed, the thermostat changed and about 1 gallon of antifreeze/water replacedOne thing I learned. TAKE OUT THE FAN/OVERFLOW assembly. Otherwise the alternator is a pain to get out.Pictures will follow. I stopped taking them after my hands got full of antifreeze. My mechanics gloves are ruined. Oh well, they are only $20 vs whatever the dealer would have charged.Belt was frustrating, but unbolting and moving the wiring harness out of the way helped BIG TIME.

[joatmon]

Quote, originally posted by johnsoax »Thanks for all the help. Started the work about about 7:15 (CST) and finished with everything, including cleaning up and test drive about 10 minutes ago. does the car now heat up correctly?

[johnsoax]

I think so.At city speeds it heats up quickly. But as soon as I got on the highway this morning, the temperature dropped, but not all the way down. It then came partway back up as I drove the 10 miles on the highway. I'm hoping the car is "relearning" how to drive and that it will all work out. After I got off the highway the temperature came right back up to where it was. At least I have heat now. And the CEL is gone.

[ToolGuy]

Quote, originally posted by johnsoax »Anybody? Can't figure out how to unplug these plugsI changed out my T-stat without removing the alternator, just moved it aside...

[johnsoax]

Good for you. I didn't want to chance anything. So I followed the procedure (plus some steps so I could complete stuff). The vibe must have more parts than the Matrix, as there are three bolts in our alternators (the two mentioned, plus a third on the top).