97 FLHTC Oil Pressure Gauge
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97 FLHTC Oil Pressure Gauge
Need some troubleshooting advice.
I have a 1997 FLHTC that shows "0" oil pressure at the gauge in the fairing. The low oil pressure light works as it should The red light comes on we the ignition is switched on and goes out when the bike starts.
I do have the manual, and I've performed the following items.
1) Checked oil pressure using a manual gauge attached to where oil pressure switch is located. I have 30psi at start-up
2) Tested the gauge per the manual by grounding the "G" terminal. The gauge moves to the high limit when grounded like it should. The manual says to replace the pressure switch.
3) Replaced the oil pressure sending switch (per the manual). The gauge till read "0".
Now, I'm wondering if I might have two bad oil sending switches or the gauge in the dash is faulty.
I cannot find anything in the manual about testing the gauge except for what I've already done (item #2).
I'm alright riding it with the gauge not functioning, but I would like to correct this issue.
Any suggestions would be appreciated.
Thanks,
Hairy Dog
I have a 1997 FLHTC that shows "0" oil pressure at the gauge in the fairing. The low oil pressure light works as it should The red light comes on we the ignition is switched on and goes out when the bike starts.
I do have the manual, and I've performed the following items.
1) Checked oil pressure using a manual gauge attached to where oil pressure switch is located. I have 30psi at start-up
2) Tested the gauge per the manual by grounding the "G" terminal. The gauge moves to the high limit when grounded like it should. The manual says to replace the pressure switch.
3) Replaced the oil pressure sending switch (per the manual). The gauge till read "0".
Now, I'm wondering if I might have two bad oil sending switches or the gauge in the dash is faulty.
I cannot find anything in the manual about testing the gauge except for what I've already done (item #2).
I'm alright riding it with the gauge not functioning, but I would like to correct this issue.
Any suggestions would be appreciated.
Thanks,
Hairy Dog
Seasoned HDF Member
Joined: Apr 2011
Posts: 6,185
Likes: 2,134
From: W. Texas
Your step # 2 pretty much says your connected to the gauge.
These gauges were never known to be real accurate.
The idiot light won't come on till 5-7 lbs of pressure IIRC.
My EVO will turn on the light on a real hot day and something of a extended idle. Long traffic light.
It's gauge will most always look like it's at 0 with above conditions.
When it really bothered me I'd give a little throttle and see the gauge move up some.
I got to where I paid no attention to it
Taking into consideration age to the gauge and related wiring It certainly could be a bit off
I put 30k + miles on the bike with it like that.
WP
These gauges were never known to be real accurate.
The idiot light won't come on till 5-7 lbs of pressure IIRC.
My EVO will turn on the light on a real hot day and something of a extended idle. Long traffic light.
It's gauge will most always look like it's at 0 with above conditions.
When it really bothered me I'd give a little throttle and see the gauge move up some.
I got to where I paid no attention to it
Taking into consideration age to the gauge and related wiring It certainly could be a bit off
I put 30k + miles on the bike with it like that.
WP
HDF Community Team
Joined: Dec 2005
Posts: 5,423
Likes: 2,621
From: NC USA
The gauge needs 3 wires - power, ground and sensor. They also work backwards from most electrical gauges. The higher the oil pressure, the higher the resistance (to ground) from the sender.
You mention grounding the "G" pegged the gauge. Was that at the sender where you grounded? Have the wires on the gauge been disturbed since it was last working?
I can see how it would behave as stated, if by chance the ground and sender wire on back of the gauge were reversed. Or if the gauge was not grounded (via wire terminal) it can't properly read the resistance from sender, possibly giving you zero or pegged.
You mention grounding the "G" pegged the gauge. Was that at the sender where you grounded? Have the wires on the gauge been disturbed since it was last working?
I can see how it would behave as stated, if by chance the ground and sender wire on back of the gauge were reversed. Or if the gauge was not grounded (via wire terminal) it can't properly read the resistance from sender, possibly giving you zero or pegged.
Set your MM to read ohms. Most of those will beep if no resistance (0 ohms) is found. Test from one end of the wire (at the sensor) to the other (at the gauge). You want 0 ohms.
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HDF Community Team
Joined: Dec 2005
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From: NC USA
I'm waiting on parts and 0maha is probably busy so apologies for upstaging...
White wire on "WK" post, green wire on "G" post. Oil light is working, so I'll leave that part out.
Switch off - sender wires connected. Meter set to ohms - "G" post to engine ground should be about 10 ohms
Switch ON - "G" post grounded with a jumper wire, gauge should peg to Zero. With green wire unhooked, gauge should peg past 40 psi.
"Tested the gauge per the manual by grounding the "G" terminal. The gauge moves to the high limit when grounded like it should."
Remember what I said - the sender/gauge works backward of conventional wisdom. More resistance at sender equals higher gauge reading. Less resistance at sender equals lower gauge reading. Unless someone has put an aftermarket or later model gauge on it, that's how they work.
White wire on "WK" post, green wire on "G" post. Oil light is working, so I'll leave that part out.
Switch off - sender wires connected. Meter set to ohms - "G" post to engine ground should be about 10 ohms
Switch ON - "G" post grounded with a jumper wire, gauge should peg to Zero. With green wire unhooked, gauge should peg past 40 psi.
"Tested the gauge per the manual by grounding the "G" terminal. The gauge moves to the high limit when grounded like it should."
Remember what I said - the sender/gauge works backward of conventional wisdom. More resistance at sender equals higher gauge reading. Less resistance at sender equals lower gauge reading. Unless someone has put an aftermarket or later model gauge on it, that's how they work.
Last edited by t150vej; Jul 24, 2021 at 12:52 PM.
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When I checked "Switch off - sender wires connected. Meter set to ohms - "G" post to engine ground should be about 10 ohms" I get a 0.00 reading.
What would the chances of getting a new pressure switch that was bad be?
What would the chances of getting a new pressure switch that was bad be?
HDF Community Team
Joined: Dec 2005
Posts: 5,423
Likes: 2,621
From: NC USA
Try to get a reading on the "G" with the engine running. If still zero (grounded), it's a bad sender.