Gauge Problem again
Thread Starter
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Senior User
Joined: Apr 2010
Posts: 368
Likes: 3
From: Loganville, Ga
Gauge Problem again
My Fuel gauge has never read correctly. Now other gauges are acting up. I strongly suspect a ground problem.
Where, physically, is the wiring harness ground located.
And just for fun, where physically does the harness get it's power to drive the gauges?
Thanks
This is on my 86 - 300ci - 4sp.
Where, physically, is the wiring harness ground located.
And just for fun, where physically does the harness get it's power to drive the gauges?
Thanks
This is on my 86 - 300ci - 4sp.
Senior User
Joined: Feb 2012
Posts: 177
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From: Grants Pass, OR
My Fuel gauge has never read correctly. Now other gauges are acting up. I strongly suspect a ground problem.
Where, physically, is the wiring harness ground located.
And just for fun, where physically does the harness get it's power to drive the gauges?
Thanks
This is on my 86 - 300ci - 4sp.
Where, physically, is the wiring harness ground located.
And just for fun, where physically does the harness get it's power to drive the gauges?
Thanks
This is on my 86 - 300ci - 4sp.
The fuel, oil and temp gauges are all 3 powered by the Instrument Voltage Regulator in the instrument panel. So if all 3 of these gauges are acting up then suspect the IVR. The IVR gets its power from the ignition switch.
The gauges are grounded at their respective senders and nowhere else.
The IVR appears to get grounded via a mounting bolt to metal in the instrument cluster.
Duralast/Instrument Cluster Voltage Regula (IVR606) | 1986 Ford F150 1/2 ton P/U 4WD 8 Cylinders N 5.0L FI | AutoZone.com
You might have a look to see if the IVR ground connection is corroded. Test the ground with an ohm meter or temporarily ground it with a jumper wire to a known good ground source and see if the gauges get better.
Here is a diagram of the instrument panel gauges:
http://imageshack.us/a/img507/4813/solsel.jpg
.
Thread Starter
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Senior User
Joined: Apr 2010
Posts: 368
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From: Loganville, Ga
I've replaced the IVR with both a used one from the salvage yard and a brand new one. No change. I also have a wire from the firewall to the engine block on the driver's side. I'll check that one.
There is a note on the page you posted. "See Grounds page 6,7) can you post those 2 pages as well?
Thank you very much!
There is a note on the page you posted. "See Grounds page 6,7) can you post those 2 pages as well?
Thank you very much!
Senior User
Joined: Feb 2012
Posts: 177
Likes: 0
From: Grants Pass, OR
Here is the ground diagram:
Note page 7 is for diesel only.
http://img850.imageshack.us/img850/9286/grounds.jpg
This is pictorial of where the instrument ground is (G701)
http://imageshack.us/a/img259/2417/ipwiring.jpg
Note page 7 is for diesel only.
http://img850.imageshack.us/img850/9286/grounds.jpg
This is pictorial of where the instrument ground is (G701)
http://imageshack.us/a/img259/2417/ipwiring.jpg
Thread Starter
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Senior User
Joined: Apr 2010
Posts: 368
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From: Loganville, Ga
No, it's behind the radio to the right as you care facing it. I remember that one when I installed my new head unit. I cut the back of my hand on it.
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Senior User
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From: Grants Pass, OR
That is the view from behind the dash as if you were sitting in the engine bay looking through the firewall.
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Im extremely new at this and am having trouble with my tach and my fuel gauge and assuming it may be the same issue you are having . I dont know how in the world yall get back there to work on stuff but i will have to give it a shot later.
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Joined: Aug 2009
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my moody gauges
I have the same truck with the same gauge issue. The amp remains the same, but the fuel, temp and oil pressure gauges all read high, medium, or low, simultaneously to one another. So I'm guessing that the voltage thing is malfunctioning, or a bad ground.
When i start the truck, the gauges may read in the middle of the range. Another day, they may read high, all of them, except the amp gauge, that never changes. Yet another time the 3 gauges will read low. The truck operates the same no matter what the gauges indicates.
Any fix for this????
Thanks in advance.
1986 300, 4 speed od 170rs. 186k miles
When i start the truck, the gauges may read in the middle of the range. Another day, they may read high, all of them, except the amp gauge, that never changes. Yet another time the 3 gauges will read low. The truck operates the same no matter what the gauges indicates.
Any fix for this????
Thanks in advance.
1986 300, 4 speed od 170rs. 186k miles
Posting Guru
Joined: Aug 2009
Posts: 2,271
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From: Mexia, TX
The gauges get power from the IVR as others have said, so I'd grab a few from your local junkyard (if you have one) and see if you can find one that gives more stable readings. Between that and the ground that's probably about all you can do aside from taking everything apart in the gauge cluster and cleaning every contact.
Though honestly, the factory gauges aren't going to be particularly accurate anyway. :\
Though honestly, the factory gauges aren't going to be particularly accurate anyway. :\
Post Fiend
Joined: Jul 2004
Posts: 8,786
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From: Northern California
G-701 Grounds the following in no paticular order...
1: Instrument Cluster ICVR
2: Instrument Cluster Illumination lamps
3: Heater and/or A/C blower switch (not the motor just the toggle switch)
4: Fuel Gauge sender from the sender to the dash
5: Seatbelt and headlamp warning buzzers
Among others...
Make sure this ground is clean and tight to the dash support to the right of the radio.
Also make sure the dash support is grounded well to the firewall. If the support is rusty, remove one of the lower support brackets that hold the dash support firm to the firewall and clean the metal ends so that good clean metal contacts each end for better grounding.
Check and clean, or replace the firewall to engine ground. Also check the engine to battery ground for good practice.
1: Instrument Cluster ICVR
2: Instrument Cluster Illumination lamps
3: Heater and/or A/C blower switch (not the motor just the toggle switch)
4: Fuel Gauge sender from the sender to the dash
5: Seatbelt and headlamp warning buzzers
Among others...
Make sure this ground is clean and tight to the dash support to the right of the radio.
Also make sure the dash support is grounded well to the firewall. If the support is rusty, remove one of the lower support brackets that hold the dash support firm to the firewall and clean the metal ends so that good clean metal contacts each end for better grounding.
Check and clean, or replace the firewall to engine ground. Also check the engine to battery ground for good practice.
FTE Legend
Joined: Jul 2010
Posts: 32,875
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From: Northeast, OK
I have the same truck with the same gauge issue. The amp remains the same, but the fuel, temp and oil pressure gauges all read high, medium, or low, simultaneously to one another. So I'm guessing that the voltage thing is malfunctioning, or a bad ground.
When i start the truck, the gauges may read in the middle of the range. Another day, they may read high, all of them, except the amp gauge, that never changes. Yet another time the 3 gauges will read low. The truck operates the same no matter what the gauges indicates.
Any fix for this????
Thanks in advance.
1986 300, 4 speed od 170rs. 186k miles
When i start the truck, the gauges may read in the middle of the range. Another day, they may read high, all of them, except the amp gauge, that never changes. Yet another time the 3 gauges will read low. The truck operates the same no matter what the gauges indicates.
Any fix for this????
Thanks in advance.
1986 300, 4 speed od 170rs. 186k miles
Thread Starter
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Senior User
Joined: Apr 2010
Posts: 368
Likes: 3
From: Loganville, Ga
I have changed out my IVR with both a new one and one from the salvage yard. No luck. My dash lights don't flicker that I have seen but they are dim. I have to remove all the blue caps to get enough light to see. But I understand that is a common issue. I will be opening up my dash this weekend to get at the G701 to clean it. I'm also going to clean some other grounds and maybe hook up some new ones. I'm pretty sure this is the problem. Just a matter of finding it.