Dash rectifier or poor ground cause this?
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More Turbo
Joined: Oct 2020
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From: Houston
Dash rectifier or poor ground cause this?
Howdy all,
My gas, oil pressure, and temp gage all moved to or very near the right peg at the same moment. Similar near full right indications have happened a few times. Would a bad ground or failing rectifier cause this. System voltage is normal; remains between 13.2 and 13.8 depending on load.
My gas, oil pressure, and temp gage all moved to or very near the right peg at the same moment. Similar near full right indications have happened a few times. Would a bad ground or failing rectifier cause this. System voltage is normal; remains between 13.2 and 13.8 depending on load.
Lead Driver
Joined: Nov 2013
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The only possible solution is to tear out the factory gauges and replace them with aftermarket units with numbers on them.
Even though Dave escaped from the re-education facility here at the Stock Gauge Anti-Defamation League (note to self: buy higher quality straightjackets next time) and is holding my family hostage, I offer this advice on my own free will.
Even though Dave escaped from the re-education facility here at the Stock Gauge Anti-Defamation League (note to self: buy higher quality straightjackets next time) and is holding my family hostage, I offer this advice on my own free will.
Moderator
Joined: Jan 2001
Posts: 56,979
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From: Virginia
As long as you do not rely on them to troubleshoot your engine, I am fine with the stock gauges. They look...well...stock.
You would think the instrument voltage regulator may be the culprit, and it very well could be. There is one common ground to the cluster, so if you were driving at night, and it was a bad ground, you would think the cluster lighting would be flickering around also.
1st thing you could try is the take it apart and put it back together trick. That fixes a lot of stuff.
If you didn't want to mess with it too much, here's the voltage regulator. https://www.dennis-carpenter.com/tru...oltage-regulat
You would think the instrument voltage regulator may be the culprit, and it very well could be. There is one common ground to the cluster, so if you were driving at night, and it was a bad ground, you would think the cluster lighting would be flickering around also.
1st thing you could try is the take it apart and put it back together trick. That fixes a lot of stuff.
If you didn't want to mess with it too much, here's the voltage regulator. https://www.dennis-carpenter.com/tru...oltage-regulat
FTE Legend
Joined: Nov 2015
Posts: 30,880
Likes: 4,117
From: Angier, NC
It may be the the gauge regulator on the back of the cluster but read this https://www.ford-trucks.com/forums/1...ical-help.html
Grounds can do funny things and sooner or later can come back and bite you so i would do them first and if that dose not fix the gauges do the regulator.
Dave ----
Grounds can do funny things and sooner or later can come back and bite you so i would do them first and if that dose not fix the gauges do the regulator.
Dave ----
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More Turbo
Joined: Oct 2020
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From: Houston
It may be the the gauge regulator on the back of the cluster but read this https://www.ford-trucks.com/forums/1...ical-help.html
Grounds can do funny things and sooner or later can come back and bite you so i would do them first and if that dose not fix the gauges do the regulator.
Dave ----
Grounds can do funny things and sooner or later can come back and bite you so i would do them first and if that dose not fix the gauges do the regulator.
Dave ----
Lead Driver
Joined: Nov 2013
Posts: 7,163
Likes: 1,170
Any rhyme or reason as to when the gauges misbehave? After turning on the headlights? Heater fan on high? AC on? Brake lights? The gauges are deliberately slow acting, so there might be a lag about 10 seconds if an external issue is the root cause.
IIRC, the gauges and IVR all get their ground to the cab via G701. The cab itself may not be well grounded. This mythical ground point is located near the radio. Rather than tear apart the dash, connect a long test jumper between the battery (-) post and the outer shell of the cigar lighter. The lighter shares the same G701, so rigging a test jumper also ensures the gauges and IVR have a good ground, regardless of the cab ground.
IIRC, the gauges and IVR all get their ground to the cab via G701. The cab itself may not be well grounded. This mythical ground point is located near the radio. Rather than tear apart the dash, connect a long test jumper between the battery (-) post and the outer shell of the cigar lighter. The lighter shares the same G701, so rigging a test jumper also ensures the gauges and IVR have a good ground, regardless of the cab ground.
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More Turbo
Joined: Oct 2020
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From: Houston
Any rhyme or reason as to when the gauges misbehave? After turning on the headlights? Heater fan on high? AC on? Brake lights? The gauges are deliberately slow acting, so there might be a lag about 10 seconds if an external issue is the root cause.
IIRC, the gauges and IVR all get their ground to the cab via G701. The cab itself may not be well grounded. This mythical ground point is located near the radio. Rather than tear apart the dash, connect a long test jumper between the battery (-) post and the outer shell of the cigar lighter. The lighter shares the same G701, so rigging a test jumper also ensures the gauges and IVR have a good ground, regardless of the cab ground.
IIRC, the gauges and IVR all get their ground to the cab via G701. The cab itself may not be well grounded. This mythical ground point is located near the radio. Rather than tear apart the dash, connect a long test jumper between the battery (-) post and the outer shell of the cigar lighter. The lighter shares the same G701, so rigging a test jumper also ensures the gauges and IVR have a good ground, regardless of the cab ground.
On the gas gauge, it has been erratic after starting and seems to correct after a block or two. The oil dives idling hot. Today all the went high on a bumpy road went smooth. I rapped on the dash and bezel and the seemed to recover. Assuming the regulator is original (mechanical) bumps and hitting the bezel might indicate the breaker contacts are bad. That's why I started the thread.
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Joined: Oct 2006
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From: East Central Ia
Sounds like the time to try an electronic regulator replacement. Remember my parents 81 Capri, they pulled in gas station next to me and ask what was wrong, all gauges were pegged high. I reached out the window and smacked top of dash hard, they all returned to normal.
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Joined: Oct 2020
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From: Houston
Yeah, that's what I was thinking. I do like the mechanical main regulators because they can be "tuned up " every couple years, but the instrument regulators dont look so repairable. At least this integated circuit is in a less beastly hot environment than an IC in the engine bay.
Lead Driver
Joined: Apr 2002
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Without power the guage needles rest to the left side. Since the needles are going to the far right it indicates that power is going to the guages and if the ground was bad the circuit would be short. I suspect the regulator is your issue.
Cross-Country
Joined: Aug 2015
Posts: 68
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From: Middle TN
I chased ground issues in my '85 for a while. Had flickering lights, gauges would peg on the high side, radio would cut out going over bumps. That all stopped when I ran a test ground from the battery to G701. I made that extra ground "more permanent" and haven't had any issues since. YMMV.
Lead Driver
Joined: Nov 2013
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IIRC, the IVR mounting bolt is also its ground. Make sure this connection is clean and tight. However, I'm not sure how the IVR is grounded beyond that. Maybe through the ribbon on the instrument cluster? The wiring diagram just shows a ground symbol with no extra details.
Given the chance to spend your time and money, I'd consider just replacing the IVR and see what happens. Dennis Carpenter offers a plug 'n play electronic replacement:
https://www.dennis-carpenter.com/tru...oltage-regulat
Homemade version here, with lots of other details:
https://www.garysgaragemahal.com/icvr.html
You can also search for "Ford IVR" or similar. The same unit was used on nearly all Fords of that era, so there's lots of info out there, such as in Mustang forums, etc.
Given the chance to spend your time and money, I'd consider just replacing the IVR and see what happens. Dennis Carpenter offers a plug 'n play electronic replacement:
https://www.dennis-carpenter.com/tru...oltage-regulat
Homemade version here, with lots of other details:
https://www.garysgaragemahal.com/icvr.html
You can also search for "Ford IVR" or similar. The same unit was used on nearly all Fords of that era, so there's lots of info out there, such as in Mustang forums, etc.
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More Turbo
Joined: Oct 2020
Posts: 529
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From: Houston
A solution....hopefully
I partially disassembled the dash to remind me how much is involved. Got to some of the connectors and wiggled what I could reach. It has been a week, and so far indications look good. If the problem comes up again, I will do a proper terminal cleaning.
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