Sweeping Gauges

[TC]

What I'm experiencing is when I start up the car both my Speedo and the Tach sweep the whole range of the gauges and then return to 0 and then the Tach starts working. This only seems to happen after the car sits for a while, like over night. Also it just started doing it, but doesn't do it after I've driven the car, like when I go to the store and run in, when I come back out and start it the gauges work normally. Just wondering if anyone has come across this before and might know what it is. Also when it does it, it will reset the trip odometer back to 0.

[trukluvr]

Re: Sweeping Gauges

TC, need more info. What year, make, and model? Any other issues appear around same time?

[TheSilverBuick]

Re: Sweeping Gauges

Have you been playing with the HP tuners?

[TC]

Re: Sweeping Gauges

It's on my '99 Camaro.

And yes I have been playing with the HPTuners, but not in about two weeks, and the gauge thing just started a few days ago. So I'm thinking it's probably not the software.

It's just weird, I start the car, then both the speedo and Tach will sweep the whole range of the gauge and then return to zero, and then the Tach will start working normal. And when I start driving the speedo works normally to.

Also this is an intermittent problem, sometimes it does it and other times it doesn't. But I does seem to do it more when the car has sat for awhile. And especially in the mornings when it's cold.

Also I have to check, but do you think it's possible that the battery is taking a crap, it is a 7 year old Optima.

[68 Valiant]

Re: Sweeping Gauges

I was going to say try disconnecting the battery for a couple minutes sometimes that helps.

[dieselgeek]

Re: Sweeping Gauges

since both the speedo and the tach work by measuring voltage pulses compared to a ground, the first thing I'd suspect is noise on your grounds. Have you installed any aftermarket electronics - radio, radar detector, keyless entry, remote start, car alarm, etc.? If so, try disconnecting and see what it does.

You could find the tach wire, it goes from the ECU to the dash (and I believe it's white), put a scope on it and see if it's actually showing voltage pulses or not. It would help you figure out whether or not the problem is in the cluster, or upstream.

[98ciHemi]

Re: Sweeping Gauges

I would agree with battery. I used to see this a lot at school. My understanding is that the computer is doing a self check and that makes the gauges sweep.

[dieselgeek]

Re: Sweeping Gauges

I would agree with battery. I used to see this a lot at school. My understanding is that the computer is doing a self check and that makes the gauges sweep.

yes, but why would the computer randomly "self check"

Another thing I'd suggest is for him to switch back to the original, default tune for his car that he saved. I'm no HPT expert, but - I know that you can change firmware versions, and that "sweeping gauge" thing is common on certain LS engine variants (C5 vettes sweep the gauges at startup, don't they?). Is there any chance that TC might have loaded a tune or firmware from another engine? one that someone gave him maybe?

I know that on Parish's G8, he actually reverted the firmware on the computer BACK one generation because the newer engine computers do not give you very many variables to edit. He flashed it back to an older version of the firmware, which gave him more tuning options.

The randomness of it all, makes me doubt this, but just throwing it out there.

[TC]

Re: Sweeping Gauges

I would agree with battery. I used to see this a lot at school. My understanding is that the computer is doing a self check and that makes the gauges sweep.

yes, but why would the computer randomly "self check"

Another thing I'd suggest is for him to switch back to the original, default tune for his car that he saved. I'm no HPT expert, but - I know that you can change firmware versions, and that "sweeping gauge" thing is common on certain LS engine variants (C5 vettes sweep the gauges at startup, don't they?). Is there any chance that TC might have loaded a tune or firmware from another engine? one that someone gave him maybe?

I know that on Parish's G8, he actually reverted the firmware on the computer BACK one generation because the newer engine computers do not give you very many variables to edit. He flashed it back to an older version of the firmware, which gave him more tuning options.

The randomness of it all, makes me doubt this, but just throwing it out there.

Let me say its done this on occasion ever since I've owned the car, but lately seems to be doing a little more. So like I said I don't think it has to do with the HPT software. Also I haven't loaded anything on my car other than the modified stock tune. Also no aftermarket electronics, even though some of the stuff you listed came with the car from the factory.

Anyway I'm kind of thinking it's a bad ground or my battery is taking a crap.

[yellomalibu]

Re: Sweeping Gauges

Thoroughly clean your battery connections and inspect the cables for signs of corrosion before ditching the battery.

my .02

[dieselgeek]

Re: Sweeping Gauges

TC, have you taken a datalog when this happens? If battery voltage is the problem, it'll show up in the log. Would be interesting to see...

[98ciHemi]

Re: Sweeping Gauges

It's a seven year old battery, it's had a good run. Mom's minivan did this when it's battery was going. If I were to guess, I would say that the voltage drops to a level low enough that the computer "thinks" it was disconnected or dead.

[TC]

Re: Sweeping Gauges

It's a seven year old battery, it's had a good run. Mom's minivan did this when it's battery was going. If I were to guess, I would say that the voltage drops to a level low enough that the computer "thinks" it was disconnected or dead.

Walt your probably right, I haven't put a volt meter on it yet, but when I turn the key to the on position the voltmeter on the dash is in the red. I'm going to do a reading tonight since I've driven the car today and then take one in the morning and see if the battery is loosing it's charge overnight. Since it seems to only do it on the first start up in the morning.

And DG it'd be cool to log it, but seems like a lot of work to just check the battery voltage. ;)

[dieselgeek]

Re: Sweeping Gauges

It's a seven year old battery, it's had a good run. Mom's minivan did this when it's battery was going. If I were to guess, I would say that the voltage drops to a level low enough that the computer "thinks" it was disconnected or dead.

Walt your probably right, I haven't put a volt meter on it yet, but when I turn the key to the on position the voltmeter on the dash is in the red. I'm going to do a reading tonight since I've driven the car today and then take one in the morning and see if the battery is loosing it's charge overnight. Since it seems to only do it on the first start up in the morning.

And DG it'd be cool to log it, but seems like a lot of work to just check the battery voltage. ;)

It would take a lot of effort to plug in a laptop and log? The reason I point this out is, if what Walt's thinking is true (I doubt it) then this means that your learned data is being lost and the car would run pretty crappy if so. I"M about 99% sure that this isn't the case. The ECU in the car will lose it's brain if it's run below about 7 volts (because it has a pair of 5v regulators that lose their ability to convert 12v to 5v, which supplies all the internal circuits their power as well as your TPS, MAP, and CKP/CMP sensors, if the battery voltage drops below about 7 volts).

If the computer is "resetting" as you guys think, you'd lose your learned data. In this case, datalogging would give you a heluva lot more information than guessing as you're doing now. Since you have the tools and skills, why would you want to guess when you could know for sure?

[urwurznitmahre]

Re: Sweeping Gauges

It's a seven year old battery, it's had a good run. Mom's minivan did this when it's battery was going. If I were to guess, I would say that the voltage drops to a level low enough that the computer "thinks" it was disconnected or dead.

Walt your probably right, I haven't put a volt meter on it yet, but when I turn the key to the on position the voltmeter on the dash is in the red. I'm going to do a reading tonight since I've driven the car today and then take one in the morning and see if the battery is loosing it's charge overnight. Since it seems to only do it on the first start up in the morning.

And DG it'd be cool to log it, but seems like a lot of work to just check the battery voltage. ;)

on that note,, the starter draw'n to many amps could in the first start of the day.. drop the battery voltage enough to cause the same computer self check.. I'l go on a limb, T.C. that you don't have the text equipment to so a draw test on thebattery.