Fan Belt Sensor - temp fix found
09-11-2011, 01:14 PM
#1
Three Wheelin'
Thread Starter
Fan Belt Sensor - temp fix found
Well - I started to get the infamous fan belt sensor warning light - despite the belt and sensor all looking fine.
I pulled the sensor (One allen bolt) and had a look. It was a bit grimy - but upon disassembly (three 5.5mm bolts) the inside was perfectly clean. I checked the harness-side connector with the ignition on and got 12 (well 13.~) volts. I checked the continuity of the microswitch and it SEEMED to be working fine. (Infinite resistance and near 0 ohms in open and closed states, respectively.)
I then checked the upstream harness (still in the engine bay) to see if there was a fault in the wires perhaps. Nothing. I put everything back together in the hopes that just that little TLC would suffice - as it sometimes does. ; )
No love. : (
So I dug deeper and took everything apart again - suspecting the microswitch. Upon more precise testing (which I agree I should have done the first time!) - the switch was NOT reliably presenting new zero ohms when pressed in. Even though I could hear it "click" the resistance didn't change. I played with it a bit and realized that if the switch was pressed further in - I got reliable performance. So...
Borrowing a concept (sort of) from the AFM "arm bending fix" - I carefully bent the metal contact arm so that the pulley assembly rocker pushed the arm further through its arc of motion and pushed the switch "more" closed.
SEEMS to have fixed the problem - but I'll confirm after some miles.
CAUTION: There DOES seem to be some risk to this - as the idler pulley arm seems to be a little less willing to spring back and push the idler wheel out - therefore opening the switch and throwing the "!" light on. Therefore - if your belt did break and the arm DID NOT extend - you might get an engine overheat scenario. You've been warned. As have I. : )
Pic below is of the sensor opened up and the bright angular metal piece is the metal arm I bent.
The BEST fix is to replace the sensor - but I'm frugal and wanted this fixed as I wait for a (soon to be) ordered new sensor.
Hope this helps someone.
RK
I pulled the sensor (One allen bolt) and had a look. It was a bit grimy - but upon disassembly (three 5.5mm bolts) the inside was perfectly clean. I checked the harness-side connector with the ignition on and got 12 (well 13.~) volts. I checked the continuity of the microswitch and it SEEMED to be working fine. (Infinite resistance and near 0 ohms in open and closed states, respectively.)
I then checked the upstream harness (still in the engine bay) to see if there was a fault in the wires perhaps. Nothing. I put everything back together in the hopes that just that little TLC would suffice - as it sometimes does. ; )
No love. : (
So I dug deeper and took everything apart again - suspecting the microswitch. Upon more precise testing (which I agree I should have done the first time!) - the switch was NOT reliably presenting new zero ohms when pressed in. Even though I could hear it "click" the resistance didn't change. I played with it a bit and realized that if the switch was pressed further in - I got reliable performance. So...
Borrowing a concept (sort of) from the AFM "arm bending fix" - I carefully bent the metal contact arm so that the pulley assembly rocker pushed the arm further through its arc of motion and pushed the switch "more" closed.
SEEMS to have fixed the problem - but I'll confirm after some miles.
CAUTION: There DOES seem to be some risk to this - as the idler pulley arm seems to be a little less willing to spring back and push the idler wheel out - therefore opening the switch and throwing the "!" light on. Therefore - if your belt did break and the arm DID NOT extend - you might get an engine overheat scenario. You've been warned. As have I. : )
Pic below is of the sensor opened up and the bright angular metal piece is the metal arm I bent.
The BEST fix is to replace the sensor - but I'm frugal and wanted this fixed as I wait for a (soon to be) ordered new sensor.
Hope this helps someone.
RK
