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windsorbill · 06-18-2015, 09:59 PM

My tach is starting to jump around. . Engine running perfectly and while on the highway tach will jump from 1500 to 2000 for a second or so and back to 1500. Where is the tach getting its signal.? isl 400.

rvtips · 06-18-2015, 11:20 PM

Quote:

Originally Posted by windsorbill

My tach is starting to jump around. . Engine running perfectly and while on the highway tach will jump from 1500 to 2000 for a second or so and back to 1500. Where is the tach getting its signal.? isl 400.

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I hope you get some answers on this,ours has been doing it for years.

Stretch · 06-18-2015, 11:54 PM

You have an electronic engine so I expect it is getting its signal from the engine computer. That said I have no idea what to do about it but contact Cummins. Could be a loose ground behind the gauge.

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windsorbill · 06-19-2015, 11:23 AM

I'm going to try running a new ground wire to the instrument panel. That should be relatively easy once we get back home from this trip.

SSRice · 06-19-2015, 12:10 PM

the tach should be easily accessible and if has this type of connectors check to make sure all are tight. Similar to the Speedometer connections

rvtips · 06-19-2015, 11:32 PM

Quote:

Originally Posted by windsorbill

I'm going to try running a new ground wire to the instrument panel. That should be relatively easy once we get back home from this trip.

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I did that and it did not help?

captw3 · 06-20-2015, 05:32 AM

I installed a ScanGauge D took 10 minutes and $135. I now have access to a ton of information including error codes and gauges that my MH didn't have.

Rick

trabuco · 06-20-2015, 09:38 PM

My temperature gauge does the same thing all connections tight and new ground wire no help. I went with the VMSPC on a 10" tablet to give me more correct info. Don't look at the dash gauges anymore.

J2Jake · 06-21-2015, 05:46 AM

I also use the Scan D. However my fuel gauge is wacko. At dealer and hopeful for repair. Scan D does not have fuel tank access. Fustrating when something does not function properly!

captw3 · 06-21-2015, 06:36 AM

Jake you can use the fuel logging function on the ScanGauge D to track use and mileage functions such as gallons to empty or miles to empty. MPG and gph can also be calculated.
Like all computerized gizmos though you can only get out information you put in and it can be a hassle to do the input.
Rick

J2Jake · 06-23-2015, 07:38 PM

Thanks Rick. I have not mastered all Scan D functions as yet but do like it. I know my mph and I keep track of mileage between fill ups. DW says it scares her. Gotta mke her feel safe!

stich · 06-24-2015, 09:24 AM

My tach pulses a regular beat along with the alt fail light and the alt gauge. Has done it for a few years now. I guess it's time for a new alt but hasn't caused me any problems yet. I assume it would be the voltage regulator acting funny. I use my Scan Gauge too.

ImNuts · 06-24-2015, 09:34 AM

My tach jumps around also. Not consistent with anything. Tried the ground but it didn't work. Bought a Scangauge D to get accurate RPM readings. Still looking for a solution for the tach...

Eaglesview · 06-24-2015, 12:48 PM

When new my 05 Dynasty had an erratic tach. Turned out to be a poor connection in the power input to the ECM.

When picked up new at the factory just a jumping tach. Then after about 1,000 miles engine would momentarily stop and restart in a reduced power mode. Then after about 30 seconds back to full power capability. Finally diagnosed by Massey's in Phoenix as poorly crimped wiring of the ECM connector. But this whole adventure included a tow job off I-5 and bent mirrors from the tow truck!