Tachometer stopped working for a second????

[cfiiman]

Hey everyone,

So I started up the Viper tonight (94 RT10) and I noticed after it started my rpm gauge kept dropping to 0 like it got disconnected or something, it came back on instantly and would drop off like no power to it or something. It did this a few times for probably 5 seconds maybe and then registred normal and I drove it about an hour with no problems, everything fine. I guess I'm trying to figure out what was going on with it, I figured if something was loose it would have kept doing it, at least when I hit bumpbs but it was just fine the whole ride, so I'm puzzled. Any ideas? Anything I should do or wait for it to happen again or what? I searched but found nothing on this any help appreciated, thanks!

 

[cruser]

How old is your battery? Mine was showing some tach issues as the battery's life was ending, even after being on a trickle charger.

 

[cfiiman]

cruser, thanks for the reply, the battery was "supposedly" changed in 07, that is what the dealer I bought it from said but who knows honestly. It doesn't start the car "weakish" at all, very strong but I know from reading that the batteries cause a lot of "weird" stuff in Vipers. Would a battery slowly going cause this just when it first started up or wouldn't just keep acting weird???? I don't know just trying to get some knowledge. Thanks!

Oh BTW, what kind of tach issues where you having, similar to mine?

 

[Slithr]

It could be that after running a few minutes the alternator brought the battery back up to full power? Sounds like a good suggestion to check the battery, 2007 was 3 years ago (which is about all I usually get out of a battery).

 

[cfiiman]

^^^^^ 4 years ago lol. I'm going to play with it tomorrow and see if it does it when first starting up, if it does i'm going to get a new battery right away. The motor starts sooooo strong though, I just wouldn't think the battery is losing anything at all based on how strong it starts the big V10.

 

[cruser]

My tach would go to zero every time I was coming to a stop and push the clutch in. It would only last a second, but would occur often. Mine would also start and run fine other than that, always left on a battery tender. Then one day the battery was dead and that was that. Mine is a 97, but as you stated these cars are very sensitive to their battery.

 

[Steve-Indy]

Agree with changing the battery regardless of other findings as it is old with an unknown status.

That will give you a needed opportunity to check the cable connectors at the battery as well as inspect and clean(and possibly paint??) the battery tray which is often in a terrible state with older Vipers.

Consulting Tony's thread will be a great help in getting you started:

http://forums.viperclub.org/illustr...y-tray-cleaning-guide-photos.html#post2522974

 

[cfiiman]

thanks guys I'll be looking into the battery, I searched a few threads on the best batt for the viper and all I really found was to stay away from optimas. What is a good recommendation I had good luck with duralast and Bosch but would like to know what others run.

 

[cruser]

I like the Diehard, but I may be biased as they are my employer.

 

[cfiiman]

Cool thanks for letting me know, anyone else?

 

[Steve-Indy]

http://forums.viperclub.org/rt-10-gts-discussions/639931-2001-gts-battery.html#post2887153

Die-Hard Gold and Platinum batteries work for us...combined with Battery Tender Plus units on all.

 

[cfiiman]

Steve thanks! Just a quick update, I took the car out for an hour cruise today, weather is stunning compared to what we have had, and no problems with the tach, even on startup, I'll be watching everything like a hawk and getting a new battery here in the next little bit. Steve, can you answer the question about if I need to set the tps sensor by pressing the pedal 5 times after replacing the batteries, or is that only newer gens?

 

[plumcrazy]

die hard or interestate for me.

could also be a cam/crank sensor that makes the tac drop off like that

 

[Steve-Indy]

I personally have had no problems with the PCM after changing batteries in Gen I's. They do "learn" quickly...from your right foot !!

For a couple of bucks (spent at a Radio Shack or at a auto parts store) you can buy an adaptor with a cigarette lighter plug on one end and two snaps on the other end that clip on to a standard 9 volt battery (like those used in smoke detectors)...then use this to keep clock, radio, PCM, etc. "alive" while you change battery...over a short period of time.

If you decide to work on the tray for an extended pe iod of time, I wouldn't worry...just fix the tray, teach PCM after the fact.

I have occasionally seen/used a different approach which I am not recommending that provides "juice" longer with the battery removed: FIRST totally isolate the disconnected positive battery cable's end clamp (isolate, insulate, and secure it away from car's metal) THEN, you CAN switch to a float charger plugged in under the hood (then quickly unplug the small 9 volt battery to be safe) OR use jumper cables from an extra battery and connect up front in the usual places under the hood...remembering that you now have more worries with a fully powered-up electrical system...noting I'm not fond of this last approach.

Hope this helps!!

Others may have better ideas.