Tachometer Stopped Working

[GT35065]

Here is why I'm waiting to fix my tach and temp guage problem. Talked to a detailer yesterday I've known for 15 years. She has a customer with a red/white stripe Ford GT in the Clearwater, FL area. A few months ago, he had the tach failure and spent $7000 to fix it. Believe tach and computer were replaced. She just detailed his car again recently, and asked him how the car was doing. He said, "don't ask, the tach has failed again". Not a happy camper. She knows his name which I won't post here, but I could find out if he is a member of the forum.

Until someone comes up with a reason why these guages are failing, I'm not going to risk 7 grand for a temporary fix. I still say we are going to see a lot more of this, and hope Ford will step up.

 

[KMCBOSS]

I'm just throwing this out there.....for what its worth.....until a reason is found for the gauge failures, I think I would quit using the plugin battery charger! I have never used the battery charger and try to drive enough to not need it (never had a gauge problem). For those of you who don't have that option disconnecting the battery may be the best option.

 

[Shadowman]

I'm just throwing this out there.....for what its worth.....until a reason is found for the gauge failures, I think I would quit using the plugin battery charger! I have never used the battery charger and try to drive enough to not need it (never had a gauge problem). For those of you who don't have that option disconnecting the battery may be the best option.

"Lady Luck" has IMO remained your friend and yet your comments are well received and your position based on personal experience is understood; thank you.

Rarely do I take a firm opposite position however I highly suggest that the battery charger be used and used regularly.

Yes I have replace a few failed gauges however at any given time I have many Ford GT's in my facility and all of them are "always" on either the OEM tender or the Battery Tender brand and I have had "no" failures with any of these gals; this has been the case for the past several years.

First of all the gel cell battery lives best when warm meaning fully charged and secondly without empirical data to present I remain convinced that electrical surges are the culprit for the failed gauges and one of the greatest surges that the system can create/experience is when starting her with a less than fully charged battery. A Forum member and I have been chatting about this issue and intend on doing some testing soon.

Takes care

Shadowman

 

[SuperB]

I don't use a battery tender at all. I live in Florida and drive at least once every 2 weeks. I've still had 2 failures, so it's NOT the tenders causing the problem, at least not for me.

I do keep it under 100 mph most of the time though, so that might be part of the problem. Maybe I just don't get the gauges wound up enough to keep them in shape?:thumbsup

 

[Empty Pockets]

...I remain convinced that electrical surges are the culprit for the failed gauges and one of the greatest surges that the system can create/experience is when starting her with a less than fully charged battery.

Takes care

Shadowman

'Any idea why FGT gauges would be so prone to failure under said conditions (or ANY 'normal' conditions for that matter), Bill? I've not had a guage failure in ANY of my cars in my whole life. None. And a few of these cars have had over 100K miles on them when sold. Some were "jump started". Some sat for long periods of time, etc.,etc., etc. You name the conditions involved & my cars have "been there" - yet 'no gauge failures.

 

[BlackICE]

'Any idea why FGT gauges would be so prone to failure under said conditions (or ANY 'normal' conditions for that matter), Bill? I've not had a guage failure in ANY of my cars in my whole life. None. And a few of these cars have had over 100K miles on them when sold. Some were "jump started". Some sat for long periods of time, etc.,etc., etc. You name the conditions involved & my cars have "been there" - yet 'no gauge failures.

Hard to have a failure if you never drive them! :lol

Now on a more serious note. The service manual labels the input to the gauges as a pulse width modulation signal (PWM), that implies the gauges take a varying duty cycle square wave as input to decide what needle position to display. The ECU gathers the information and presents it over CAN-Bus to the Gauge control module that converts Can-bus messages into a PWM signal. That means the gauges have a lot of digital electronics in them, electronics that a susceptible to damage from fluctuations in supply voltage. The specs for many common ICs used have a maximum voltage range of in the range of 18v. If the voltage gets higher than that damage may occur. Any positive voltage spikes exceeded the max, or any negative spikes may kill ICs used in the gauges. I am not saying this is happening, only that it is a probable cause. Voltage spikes are a fact of life in an automobile! They come from motors turning on and off (starter, windows, etc), the alternator cycling, HID headlight controllers, etc. Proper designs should account for this and protect sensitive circuits as required.

 

[Empty Pockets]

Hard to have a failure if you never drive them! :lol

Now on a more serious note. The service manual labels the input to the gauges as a pulse width modulation signal (PWM), that implies the gauges take a varying duty cycle square wave as input to decide what needle position to display. The ECU gathers the information and presents it over CAN-Bus to the Gauge control module that converts Can-bus messages into a PWM signal. That means the gauges have a lot of digital electronics in them, electronics that a susceptible to damage from fluctuations in supply voltage. The specs for many common ICs used have a maximum voltage range of in the range of 18v. If the voltage gets higher than that damage may occur. Any positive voltage spikes exceeded the max, or any negative spikes may kill ICs used in the gauges. I am not saying this is happening, only that it is a probable cause. Voltage spikes are a fact of life in an automobile! They come from motors turning on and off (starter, windows, etc), the alternator cycling, HID headlight controllers, etc. Proper designs should account for this and protect sensitive circuits as required.

I said, "2 X 2 = 4". YOU said, "When two positive even integers, such as the even integers two & two, are multiplied together, the resulting product will also be a positive even integer, which, in this particular example, would be four." :rofl

But, ya! DAT's basically whut I wuz tryin' ta say, thar, 'ICE! "Voltage spikes are a fact of life in an automobile. Proper designs should account for this and protect sensitive circuits as required." I wuz jus' tryin' ta be a bit more diplomatic! Thanks for blowing my cover!!!:lol




(BTW, what part of, "...a few of these cars have HAVE HAD OVER 100K MILES ON THEM when sold", did you miss? :tongue :slap)

 

[BlackICE]

(BTW, what part of, "...a few of these cars have HAVE HAD OVER 100K MILES ON THEM when sold", did you miss? :tongue :slap)

You must have bought those cars used with 99,999.9+ miles on the odometer. :lol

 

[BlackICE]

I said, "2 X 2 = 4". YOU said, "When two positive even integers, such as the even integers two & two, are multiplied together, the resulting product will also be a positive even integer, which, in this particular example, would be four." :rofl

I was just trying to be as through as Indy for Frank's benefit. :biggrin

 

[Empty Pockets]

You must have bought those cars used with 99,999.9+ miles on the odometer. :lol

:tap: :skep :dead:

 

[Empty Pockets]

I was just trying to be as through as Indy for Frank's benefit. :biggrin

Well, ya lost me at: "The service manual labels the input to the gauges...":willy:willy:willy

 

[BlackICE]

Well, ya lost me at: "The service manual labels the input to the gauges...":willy:willy:willy

Google is your friend. Do a search and get an education. :biggrin

 

[Empty Pockets]

Google is your friend. Do a search and get an education. :biggrin

'Too old... :frown

 

[RALPHIE]

Sounds like filter may be in order - to absorb and minimize voltage spikes above a given frequency, thus ensuring that voltages above the maximum threshold cannot reach the gauges.

 

[Shadowman]

Sounds like filter may be in order - to absorb and minimize voltage spikes above a given frequency, thus ensuring that voltages above the maximum threshold cannot reach the gauges.

This is in the works; or I should say that the testing to validate that this could solve the problem is

Takes care

Shadowman

 

[KMCBOSS]

"Lady Luck" has IMO remained your friend and yet your comments are well received and your position based on personal experience is understood; thank you.

Rarely do I take a firm opposite position however I highly suggest that the battery charger be used and used regularly.

Yes I have replace a few failed gauges however at any given time I have many Ford GT's in my facility and all of them are "always" on either the OEM tender or the Battery Tender brand and I have had "no" failures with any of these gals; this has been the case for the past several years.

First of all the gel cell battery lives best when warm meaning fully charged and secondly without empirical data to present I remain convinced that electrical surges are the culprit for the failed gauges and one of the greatest surges that the system can create/experience is when starting her with a less than fully charged battery. A Forum member and I have been chatting about this issue and intend on doing some testing soon.

Takes care

Shadowman

Thanks for not beatin' me up too bad Bill. Ed

 

[Shadowman]

Thanks for not beatin' me up too bad Bill. Ed

You are a good man and I felt awkward even making the post however I had a greater fear that across the land battery tenders were about to be unplugged.

Two issues;

1. The battery must be kept warm aka charged regardless as to how; by exercising her regularly or keeping a battery tender on her.
2. The root cause of the issue need be defined; I think that we have a handle on this however testing needs to be completed to validate it.

All the best Ed

Shadowman

 

[clements]

i am a know nothing compared to most of you who post on this forum and i have not lost any gauges yet. i have been following this issue because of the cost and trouble to replace gauges waiting for someone to suggest a solution. i have great respect for shadowman and his suggestion that surges from a poorly maintained or damaged battery might be the problem. until someone comes up with a fix maybe those of us who are seasonable drivers should start every year with a fresh battery. could be cheap insurance.

 

[GT35065]

Just keep a tender on it. If you want to be extra safe, disconnect the terminals for long term storage. These batteries will last for years if properly maintained.

 

[DataDale]

I'm going to contact the gauge suppiler for best practises and any possible support they could offer you guys. It's not the Batteries.