False Coolant Temperature Alarm.

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Peter Mann
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Joined: 03 Feb 2003, 18:42
Location: Australia
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False Coolant Temperature Alarm.

Post by Peter Mann »

On my late ’94 Xantia, the coolant temperature alarm is lighting up intermittently, while the temp gauge is is showing a “normal” temperature of 82 to 87 degrees. This is a manual gearbox version, and the original thermostat is stamped with 89C. I’ve tested the thermostat in a water bath with a candy thermometer, and it reaches full open at 89 degrees Centigrade, and the cooling system is in impeccable condition. Is there a second temperature transducer for the computer (location please), or some other explanation for this anomoly ?
wheeler
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Post by wheeler »

is the cooling fan on whenever the warning lamp iluminates ? does the car have a bitron unit ?
Peter Mann
Posts: 9
Joined: 03 Feb 2003, 18:42
Location: Australia
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Post by Peter Mann »

<BLOCKQUOTE id=quote><font size=1 face="Verdana, Arial, Helvetica" id=quote>quote:<hr height=1 noshade id=quote>
is the cooling fan on whenever the warning lamp illuminates ? does the car have a bitron unit ?
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Yes, the cooling fan was running, which on this car is so unusual that I've not noticed it before.
What is a bitron ? . . . she has refrigerated airconditioning, which was operating at the time the warning light was falsely triggering.<font size=4></font id=size4><font color=blue></font id=blue>
wheeler
Posts: 6848
Joined: 21 Sep 2002, 19:07
Location: United Kingdom
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x 717

Post by wheeler »

a bitron unit is a little black box (with 15 pin connector) located under the lefthand headlamp which controls the cooling fan/temp warning/aircon.is there a cooling fan switch in the radiator ? if its in the radiator it wont have a bitron unit.if fitted with a bitron box it gets its temp info from the brown sensor in the thermostat housing. with the a/c switched OFF does the fan kick in whenever the lamp falsely illuminates then go off when the lamp goes off ? if this is the case then it will likely need a wiring modification,i cant remember the pin numbers off hand ill have to check.let me know if it has the bitron.
Dave Burns
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Post by Dave Burns »

I had the same condition on my td a few months ago, I cleaned the plug and socket contacts in the brown temperature sensor on the thermostat housing and also on a few other plugs and sockets connecting to the engine loom near by, don't know for sure which one was the culprit but this cured the condition.
Dave
wheeler
Posts: 6848
Joined: 21 Sep 2002, 19:07
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Post by wheeler »

hi Dave,it likely will be a connection fault this is where the wiring mod i was talking about comes in,the wires from the brown sensor connect to the bitron box but go through the inner wing connector and this is where the bad connection usually is.the mod is just baisically running the wires direct from the sensor to the bitron box direct & missing out the bulkhead connector.ill have to look out the pin numbers.peter,you could try doing what dave said first,you might be lucky.
Edited by - wheeler on 06 Feb 2003 22:14:19
Peter Mann
Posts: 9
Joined: 03 Feb 2003, 18:42
Location: Australia
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Post by Peter Mann »

Thanks for your replies. Figuring that out on my own would have been really tough.
Searched in vain for thermal transducer in radiator or bitron unit under LHS headlight. However, I did notice a bronze finger protruding into the rear of the thermostat housing while I was checking the thermostat operation, so it is reasonable to take it that this Xantai has a thermal transducer at the thermostat.
Hunting around, I found a white device (approx 30mm across and 60mm down) on the inside of the LHS wing, opposite to the battery. This has a cable with a connector plugged into it that is of dimensions which would accommodate 15 pins. An ePhoto of this device is available, but how to attach it to this ?
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