darcy
Aurora Newbie
Posts: 3 
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Post by darcy on Aug 24, 2015 12:36:51 GMT -6
Hello, I'm new to this forum and stumped on this problem.
1995 Oldsmobile aurora 4.0L 42,000KM
With the key in the run position the temp guage is full pinned hot. Traction control turns off as well as air conditioning.
If I cycle the key the guage will lower some yet the car still tells me it overheating.
continue cycling the key and the temp guage reads different every time. And still overheating.
if you try driving the car it becomes underpowered periodically when this false.overheating issue is created.
I replaced the ECT because the wave form generated on the scanner showed momentary spikes from 93 to 151degrees celsius.
has anyone experienced.this problem?
Thanks very much.
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Post by sall on Aug 24, 2015 12:43:40 GMT -6
Bad replacement ECT sensor?
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Aug 24, 2015 13:07:18 GMT -6
Its a thought but I seriously have my doubts. I'm thinking a bad PCM however I'm not convinced. Is there a.test.procegure to diagnose a failed PCM?
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Post by sall on Aug 24, 2015 18:55:13 GMT -6
You can check the ECT sensor readings with a scantool if you have one available. I'm not sure what else goes on with it in between the cluster and PCM. I'd have to look in the FSM when I get a moment.
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Aug 25, 2015 5:26:31 GMT -6
I do have a scan tool. A snap on ethos. I replaced the ECT because of an erratic wave form shown on the scanner. The ECT connector and wires appeared to be in good shape.
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Aug 25, 2015 5:27:35 GMT -6
Also I'm not familiar with the abbreviation FSM?
Thanks again
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Post by wfooshee on Aug 26, 2015 6:03:36 GMT -6
Factory Service Manual.
You need one. You can find them one eBay for not a lot of money, I got my 3-volume set for my '98 for 25 bucks.
They are vital to the type of troubleshooting you're trying. Electrical schematics and troubleshooting steps in sequence. Without it you might as well be trying to work on an F-22 radar system.
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Aug 26, 2015 8:57:57 GMT -6
Thanks for the info. Ordered FSM Last night. Unfortunately I won't see them until the first week in September and the car is not driveable at this point.
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Post by sall on Aug 26, 2015 16:05:47 GMT -6
It is possible the instrument cluster is bad or at least that circuit in it according to the FSM.
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Aug 27, 2015 6:28:32 GMT -6
That being said, would the pcm receive the signal from the cluster or the ect sensor to activate limp mode and the on screen display warnings of engine hot? When this car car acts up its only for a moment then it runs perfect again for a few minutes, then it acts up again. This cycle of acting up and running great is continuous.
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Aug 27, 2015 6:31:01 GMT -6
Also would a cluster from a 1997 or 1998 fit in a 1995?
Thanks again
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Post by sall on Aug 27, 2015 7:21:43 GMT -6
I'm not sure TBH. I am sure it is all in the manual somewhere. I know you want to get on the road ASAP. Unfortunately no only a '95 cluster works in a '95 according to the parts list. www.weekendwars.com/aurora/parts/classic.pdf |
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Aug 27, 2015 7:45:31 GMT -6
Thanks for your help. I was able to find a video on YouTube with basically the same symptoms as my car. I did a google search ect sensor 1995 Oldsmobile aurora and its the first video that comes up. Maybe if you watched the video my symptoms will become more clear.
sorry to be a pain
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Post by wfooshee on Aug 27, 2015 20:40:02 GMT -6
'95 is way different electronically from later cars, as '96 up are OBD-II, '95 isn't. That difference permeates just about every system in the car.
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Post by sall on Aug 28, 2015 8:04:10 GMT -6
^Right, but a 96 cluster on works in a '96, 97-98 use same cluster and '99 uses a different cluster. There are many differences such as this on the Classics.
I watched the video. Other than a malfunctioning ECT, pretty much the only options are the cluster, PCM or wiring in between. Sorry I can't help more.
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Aug 30, 2015 18:40:20 GMT -6
Well thanks for taking the time. I'll wait for the FSM to show up before going any further.
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bobsblue95
Super Moderator 
Scars of pleasure, scars of pain. Atmospheric changes make you sensitive again.
Posts: 3,125
Staff Member
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Post by bobsblue95 on Aug 31, 2015 8:13:17 GMT -6
When you get that, first thing I'd check is continuity of the wiring from Temp sensor to PCM.
Scratch gauges off your list. PCM drives the gauges... If the gauge cluster was bad and simply showing a false reading, there would not be an overheat warning from the PCM.
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Sept 3, 2015 13:01:35 GMT -6
Thanks for the response. I figured that the pcm sent signal to the guage. So if continuity is good I suspect the PCM unless there is other sensors on the same circuit?
Have a great day
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darcy
Aurora Newbie
Posts: 3
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Post by darcy on Sept 9, 2015 7:57:13 GMT -6
Update
I haven't received the FSM yet.
On the weekend l unplugged the ECT sensor and started the car. It runs fine with the air conditioning turned on. With it off it runs a little sluggish but still driveable. I'll be checking the continuity of the Ect sensor harness to the PCM as soon as I figure out which pins in the connector at the PCM read the sensor.
Have a great day
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