Tach shuts down while driving
Tach shuts down while driving Driving yesterday the car stumbled and missed for a second then the tach dropped and wasn't working. The car ran fine during this but then about 10 sec later the tach started working again. Anyone have any idea what may have caused it? It happened twice yesterday.
the engine computer or PCM communicates to the dash cluster via closed area network (CAN). it's a computer network and a data stream. if the car stumbled, at low rpm? then my guess is electrical voltage would have dropped which may have caused bad data somewhere, and caused various things to reset... one being the rpm gauge.
other possibility is having bad wiring some where, while car is running vibration could be causing a bad connection or short causing an intermittent problem... or you might have a PCM going bad, or the stepper motor in the cluster that moves the rpm needle is going bad... not knowing history of car i can only speculate and the above is based on an unmodified car that's been taken care of but is also 10+ years old.
other possibility is having bad wiring some where, while car is running vibration could be causing a bad connection or short causing an intermittent problem... or you might have a PCM going bad, or the stepper motor in the cluster that moves the rpm needle is going bad... not knowing history of car i can only speculate and the above is based on an unmodified car that's been taken care of but is also 10+ years old.
Thanks for the reply. Yes it was at low RPM(under 2500) My tuner suggested a low voltage issue may be it as well. The history of the car is 49k miles well taken care of but nothing drivetrain wise is stock any longer. the only wiring changes have been for the N20 set up. I do have a N20 controller that the window switch runs off the tach signal. The relay on the N20 system went out a couple weeks ago and I had to replace it. I did notice yesterday during warm up it seemed like the dash lights on the radio were pulsing more than usual at idle. The car does vibrate quite a bit due to the aggressive set up. I'm going to get into it today to see if I can find anything loose obvious. Thanks again for any advice
TECH Enthusiast
Joined: Nov 2011
Posts: 587
Likes: 12
From: Connecticut SE shore
I know the '99's have an issue where low voltage can do this to the instrument cluster. Don't know if it still shows up in later years due to a weak battery and/or an alternator not doing its job.
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Verdad Gallardo Yes the second time it happened the light came on. I drove straight to autozone and it was a crank position sensor code. I don't recall which but I already had suspicions it was related to it so I put up in the air and it was an easy fix
Launching!
Joined: Mar 2004
Posts: 223
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From: Apple Maggot Quarantine Zone
I just dealt with something similar this week. Got stuck in traffic, and ended up crawling for over an hour. Had defroster on front and rear, headlights on, stereo on, and never really broke 15mph. Ended up losing most of the gauges, and idling really odd. Found voltmeter reading about 10v. Killed all of the accessories and raised the RPMs in neutral when possible, and voltage climbed right back to 14v.
I was just expecting too much at idle from the alternator. Investigating buying a smaller pulley, to keep RPMs up at lower engine speeds.
I was just expecting too much at idle from the alternator. Investigating buying a smaller pulley, to keep RPMs up at lower engine speeds.