Overheat Exhaust System light is on. *researched
08-06-06, 06:36 PM
#1
Overheat Exhaust System light is on. *researched
Hi, I have done some research about the "Overheat Exhaust System" light and I couldn't come up with any good details about what's going on with the light. I emailed the last owner and he told me that the light has been ignored for years, I know that isn't right cause I was reading this other thread and says don't ignore that light or something will cause the car to overheat.
What should I do? What to look for? Do I need any replacement?
The car doesn't get heat up or anything, and I looked everywhere too, everything seems fine. The car does have a RB header, a high flow cat, and a muffler as well.
Any opinions or advices will be much appreciated. Thank you!
What should I do? What to look for? Do I need any replacement?
The car doesn't get heat up or anything, and I looked everywhere too, everything seems fine. The car does have a RB header, a high flow cat, and a muffler as well.
Any opinions or advices will be much appreciated. Thank you!
08-06-06, 07:07 PM
#4
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check if its still bolted up, if it is then ur exhaust is getting too hot(obviously) and theres a problem in it, like a clogged cat or something like that.its never happened to me so im just talkin from wat i know(which is not much)
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08-06-06, 11:39 PM
#12
its a little sensor under the carpet under the seat on some cars, and in the trunk on older stuff like my
rx5.
there was 2 wires going to it and if the exhaust gets hot enough it will heat up the
floor in the car and get the little sensor hot enough to switch the light on.
the sensors do fail and make the light stay on all the time.
does the light come on as soon as you start the car?
if so the sensor is bad.
a quick check would be to run the car till the light comes on and feel under the carpet
and see if the floor feels hot.
thats all this warning light does, it doesn't effect the engine at all.
it only warns you that the floor is getting hot and that it might catch fire
no big deal
matt
rx5.
there was 2 wires going to it and if the exhaust gets hot enough it will heat up the
floor in the car and get the little sensor hot enough to switch the light on.
the sensors do fail and make the light stay on all the time.
does the light come on as soon as you start the car?
if so the sensor is bad.
a quick check would be to run the car till the light comes on and feel under the carpet
and see if the floor feels hot.
thats all this warning light does, it doesn't effect the engine at all.
it only warns you that the floor is getting hot and that it might catch fire
no big deal
matt
Last edited by now; 08-06-06 at 11:41 PM.
08-07-06, 03:01 AM
#14
Are the heat shields still on the car? The light is a warning that the exhaust is too hot, obviously, but it can also indicate a plugged exhaust system, timing may be off or the fuel mix if off. That is where the danger/damage can lie.
If the exhaust is not plugged, check the timing and afr's. If they are in spec, don't sweat it.
If the exhaust is not plugged, check the timing and afr's. If they are in spec, don't sweat it.
08-07-06, 09:05 AM
#15
the light should really say "the floor over the exhaust is overheating"
yes plugged exhaust could cause the floor to get to hot as well as timing or afr or shields
being off but it still would require a little driving time to make the heat to heat the floor.
if you start the car and the light comes on right away or comes on within 4 or 5 mins of
running i would guess that it has not run long enough to heat the floor.
unless there is a hole in the exhaust pointing up right where the sensor is on the floor.
matt
yes plugged exhaust could cause the floor to get to hot as well as timing or afr or shields
being off but it still would require a little driving time to make the heat to heat the floor.
if you start the car and the light comes on right away or comes on within 4 or 5 mins of
running i would guess that it has not run long enough to heat the floor.
unless there is a hole in the exhaust pointing up right where the sensor is on the floor.
matt
08-07-06, 11:59 AM
#17
Too old to act my age
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Make sure the air tube is plumbed into the cat. A cat will get very hot if the fuel mixture is too rich, allowing a lot of unburned fuel into the exhaust.
08-07-06, 12:05 PM
#18
love the braaaap
I believe the official use for that sensor is to indicate if your cats are clogged. A clogged cat will heat up enough to switch on the sensor, turning a light on in the dash. I would first check the sensor to make sure its working properly. If it is, chances are there is something wrong with the cats.
10-20-11, 07:43 AM
#20
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Old thread, right topic.
new to us '82, rat's nest gone, Ex. Heat warning light always on, right from start, custom exhaust, cat long since gone. I think if the ECU does NOT get power from the sensor (I THINK the sensor is NC (normally closed) and OPENS when hot, interrupting circuit to ECU, triggering light), it turns on the warning light, unplugging the sensor doesn't stop the light, jumping the connector doesn't either (because there's no power there I suspect, didn't think to check last night. My new thought is:
use switched power from fuel pump switch in center console (added by us). Feed power from this back to harness to tell temp light to shut off, if fuel pump circuit looses power for any reason the light will come on and act as a " your fuel pump is off" idiot light.
So we can kill "fix" the annoying light AND get a useful idiot light at the same time....in theory.....right?
new to us '82, rat's nest gone, Ex. Heat warning light always on, right from start, custom exhaust, cat long since gone. I think if the ECU does NOT get power from the sensor (I THINK the sensor is NC (normally closed) and OPENS when hot, interrupting circuit to ECU, triggering light), it turns on the warning light, unplugging the sensor doesn't stop the light, jumping the connector doesn't either (because there's no power there I suspect, didn't think to check last night. My new thought is:
use switched power from fuel pump switch in center console (added by us). Feed power from this back to harness to tell temp light to shut off, if fuel pump circuit looses power for any reason the light will come on and act as a " your fuel pump is off" idiot light.
So we can kill "fix" the annoying light AND get a useful idiot light at the same time....in theory.....right?
Last edited by jvandyke; 10-20-11 at 07:51 AM.
10-20-11, 08:34 AM
#21
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maybe I have that wrong, maybe the heat sensor is NO, normally open and closes with heat. According to FSM, jumpering the harness should cause it to be on, but mine is on while disconnected completely, so PO must have done something interesting during rat's next deletion, or ECU is messed up.
10-20-11, 09:44 AM
#22
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I will check for voltage at the harness connector of the sensor, if there, oh well, will take out bulb, if not, will supply via fuel pump circuit and see if it goes out. BTW the "no edit after 30 minutes" rule is a bother.
10-20-11, 03:39 PM
#23
Stupid question, is the small glass fuse under the dash at the ecu blown?? when I was young and dumb myself and another rotorhead pretty much gutted the interior tracing wires and was swapping the ecu when we found a blown fuse 10 sec later... problem solved.
10-20-11, 10:20 PM
#24
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I will go out and see if I can find said fuse.
I did run the wire as stated above and it does function as intended, the 12v feed shuts the stupid light off, if the fuel pump circuit goes dead (either the switch is off or any other reason) the light comes back on as a "fuel pump off warning light" but it does only work with car running, not just with the key on.
I did run the wire as stated above and it does function as intended, the 12v feed shuts the stupid light off, if the fuel pump circuit goes dead (either the switch is off or any other reason) the light comes back on as a "fuel pump off warning light" but it does only work with car running, not just with the key on.
