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Lilchief
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JUL 29, 05:59 PM
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Seems my fan isn't working on my new 88 coupe 4 cylinder. I looked for the switch on the head and couldn't find it. Also where is the relay at . Thanks Rick
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Patrick
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JUL 29, 06:17 PM
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I believe with the '87 and '88 dukes that the ECM controls the rad fan.
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Lilchief
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JUL 29, 07:28 PM
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So which sensor, ecm temp or gauge temp or does one do it all ? Think I saw 2 sensors by the water outlet. I'm use to my 85 so 88 is a little different. Thanks
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Patrick
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JUL 29, 08:09 PM
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All I know is that there's no fan "switch" on '87-'88 dukes like there is on all the other Fiero engines. I wouldn't be surprised if this is all covered in the Ogre's Cave.
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Gall757
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JUL 29, 09:17 PM
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The ECM gets temp readings from the Coolant Temp Sensor. Could be it is bad.
 [This message has been edited by Gall757 (edited 07-29-2019).]
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Patrick
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JUL 29, 09:35 PM
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Just so we're all clear, that image above is not an '87-'88 duke.
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Gall757
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JUL 29, 09:44 PM
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| quote | Originally posted by Patrick:
Just so we're all clear, that image above is not an '87-'88 duke. |
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Did the remaining sensors change location in '87 & '88?
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Patrick
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JUL 29, 09:50 PM
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| quote | Originally posted by Gall757:
Did the remaining sensors change location in '87 & '88?
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Off hand, I don't know. I do know that the '87-'88 duke got a MAT sensor. I just didn't want the OP to think from the diagram that his '88 had a Coolant Fan Switch.
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Blacktree
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JUL 31, 12:25 PM
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Like Patrick said, the '87-88 Duke doesn't have a fan switch. The ECM acts as the fan switch. It uses input from the coolant temperature sensor to determine if the fan needs to be on. The coolant temp sensor should be on the thermostat housing.
The coolant temperature sensor is just a variable resistor. As the sensor ages, the resistor will degrade. And as a result, the activation temperature of the cooling fan will be skewed. You can check the accuracy of the sensor with an Ohm meter and a thermostat. Measure the resistance of the sensor (across the 2 terminals), and compare it to the actual temperature, using the chart below. If the resistance is significantly different from what's specified on the chart, you should replace the sensor. Because that sensor also affects fueling. AND it helps the ECM determine if it should be in open or closed loop mode.
That said, if your radiator fan isn't coming on at all, it's probably a bad relay. Because if the coolant temperature sensor is completely dead, it'll throw a trouble code. Also, turning on the A/C should turn on the fan (the A/C bypasses the temperature sensor). If the fan doesn't turn on with the A/C, then the sensor isn't your problem. BTW, the fan relay is up front, below the driver side headlamp assembly.[This message has been edited by Blacktree (edited 07-31-2019).]
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Vicophine
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AUG 01, 12:25 PM
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I have this exact same issue on my 88 4-cylinder, and found a weird little solution.
When I turned on the AC (hot or cold, does not seem to matter), the front radiator fan kicked into gear.
Just something to maybe try, hope this helps.
EDIT: Wow, totally missed what Blacktree said, yup, follow that exactly.[This message has been edited by Vicophine (edited 08-01-2019).]
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