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Please help...I've searched all over the internet but cannot find an answer. Car runs fine when cold on up to about 30min of driving. Temp gauge shoots all the way to hot putting the car in limp mode, then the gauge will shoot back to normal. Sometimes it stays in limp mode and the gauge stays at hot up until I put I put the car in park, then it goes to normal and goes out of limp mode...I know about the block test yada yada and all of that, but that's not the issue. I had read about replacing the ECT sensor because it sounded like that could be the problem. I checked the harness to the ECT sensor and it's fine. So, I replaced the sensor and the car still does the same thing...please help...the engine codes aren't throwing anything that seems to coincide with the problem....could it be the PCM, or ECM. I need the issue fixed ASAP because I have to travel 80mi for work in 5days. Any advice or experience with this issue would be greatly appreciated.
 

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Discussion Starter #3
Only one I got was p1258 which is engine coolant over temperature... Which I'm assuming is normal anytime the gauge shoots all the way to hot
 

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White Diamond '03 DHS (with DTS floor shift)
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Please help...I've searched all over the internet but cannot find an answer. Car runs fine when cold on up to about 30min of driving. Temp gauge shoots all the way to hot putting the car in limp mode, then the gauge will shoot back to normal. Sometimes it stays in limp mode and the gauge stays at hot up until I put I put the car in park, then it goes to normal and goes out of limp mode...I know about the block test yada yada and all of that, but that's not the issue.
What makes you think that is not the issue?
Do the block test before you start throwing parts at it.
 

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Discussion Starter #5
I'm not loosing any coolant either

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The engine isn't overheating because sometimes it'll happen when I first start the car...the needle shoots to hot like a bullet for a split second then goes down to cold

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Post your codes with definitions... Something may be related.

A mod needs to combine this and your N* engine forum posts into this forum. Please dont double post.
Sorry about double posting
 

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White Diamond '03 DHS (with DTS floor shift)
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Ahh, I see. That DOES sound like a bad ECT sensor.

EDIT:
Double post deleted.
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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iam, You are clicking the "report post" tab and sending some of your posts to the Admin spam check forum.
 

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Discussion Starter #10
Does anyone know....I'm lost and don't know what to do at this point...I need it running right before Tuesday

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iam, You are clicking the "report post" tab and sending some of your posts to the Admin spam check forum.
I'm sorry I meant to hit quote
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Instant gauge changes sound like an electrical problem rather than mechanical or coolant. The ECT sender is a variable resistor - it changes the voltage in response to coolant heating. Depending on the circuit used, an intermittent wire break or a short would cause rapid gauge changes.
 

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I'd unhook it and see what happens... Ect that is... Question, are the fans coming on when it does say overheated? Do they come on when ac turned on also. Not that they do anything at speed...
 

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Discussion Starter #13
I'd unhook it and see what happens... Ect that is... Question, are the fans coming on when it does say overheated? Do they come on when ac turned on also. Not that they do anything at speed...
Yes I unhooked the harness to the ECT sensor and the fans came on and the rpms sat at about 1000...the fans only come on with the ac if it's hot outside...but since it's really cold now they otherwise don't come on
 

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Discussion Starter #14
Instant gauge changes sound like an electrical problem rather than mechanical or coolant. The ECT sender is a variable resistor - it changes the voltage in response to coolant heating. Depending on the circuit used, an intermittent wire break or a short would cause rapid gauge changes.
But it only does it when the cars in drive after driving for about 30min...put it in park then it's fine
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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But it only does it when the cars in drive after driving for about 30min...put it in park then it's fine
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I checked the harness to the ECT sensor and it's fine.
So, I replaced the sensor

did you use a genuine ACDelco ETC sensor -
if not - replace it -

a real shot-in-the-dark -
disconnect BOTH battery cables -
and touch them together for a couple seconds -

this SOMETIMES helps - sort of like re-booting a computer -
it will erase/clear the memory in some of the modules -

if that doesn't work -
start inspecting the wiring for chaffing/rubbing to a ground -
 

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Discussion Starter #16
===========================
I checked the harness to the ECT sensor and it's fine.
So, I replaced the sensor
did you use a genuine ACDelco ETC sensor -
if not - replace it -

a real shot-in-the-dark -
disconnect BOTH battery cables -
and touch them together for a couple seconds -

this SOMETIMES helps - sort of like re-booting a computer -
it will erase/clear the memory in some of the modules -

if that doesn't work -
start inspecting the wiring for chaffing/rubbing to a ground -
I will try the battery scenario in a bit...but I'm a little confused....I understand car manufacturers recommend their own products but why would auto stores sell off brands that are brand new that wouldn't work, if you're saying I should have purchased an ac delco sensor?
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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Take a look at the number of ECT sender choices for your engine - in www.rockauto.com. The brand names vary considerably - and most of those are made by the exact same company, whatever company that is. AC Delco does not make very many parts any more - they set specifications and outsource their products under contract.

That said, there are some "deep discount" auto parts chains that source "parts" from some really questionable manufacturers. Over many years of fooling with cars, parts, and suppliers you develop a sense for which "parts manufacturers" are good and which are best to stay away from.

Because someone may not have the luxury of having a background of car hobbying or being a schooled tech, we usually recommend stuff that we have had good experience with.

The sheer number of auto parts suppliers and manufacturers - still in the U.S. - is mind boggling, and to try to recommend widget A from Gates and widget B from Stant and widget C from Dayco gets difficult - and all 3 of those manufacturers supply GM OEM parts ............ that get packaged in AC Delco bags and boxes.
 

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White Diamond '03 DHS (with DTS floor shift)
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I will try the battery scenario in a bit...but I'm a little confused....I understand car manufacturers recommend their own products but why would auto stores sell off brands that are brand new that wouldn't work, if you're saying I should have purchased an ac delco sensor?
$$$$$$$$$$$$$$$$$$$$$$$$$
 

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Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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19,250 Posts
I will try the battery scenario in a bit...but I'm a little confused....I understand car manufacturers recommend their own products but why would auto stores sell off brands that are brand new that wouldn't work, if you're saying I should have purchased an ac delco sensor?
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why would auto stores sell off brands that are brand new that wouldn't work,
one word - PROFITS -

back in the 70's in Illinois - there was an auto parts chain called TRAK Auto -

they made K-Mart brand stuff look good -

the vast majority of their "house brand" parts were pure junk -
and failed in a very short time - if they worked at all -
yes - they folded -

AutoZone is getting that reputation with their DURALAST - house brand junk -
we "lovingly" refer to as DONTLAST -
generally speaking - it is the cheapest stuff they can get away with -

you're saying I should have purchased an ac delco sensor?
certain things - including this sensor - YES -
 
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