Tachometer

[sammcabee]

The TAC in my 2004 Alpine Coach (Cummins 400) has stopped working; always reads 600 RPMs. Currently at Clinton OK headed to Virginia and would prefer to get it fixed when I get home. Main concern is not to exceed the 2600 limit on a steep downhill. Can I limit the RPMs appropriately by monitoring my speed and gear selection?

[Full.Monte]

I think you are going to like it here on the forum!
It appears you have been using your hearing to monitor the rpms so far anyway, with that TAC showing 600 rpm all the time. I think there is little danger. Do you have an exhaust temp gauge? On uphill grades, that's the one I keep an eye on with my diesel trucks. On the downhill, you have a remote chance of over-revving the engine. But with everything in Rving, the old phrase "take it easy" applies. If it were my rig, I'd wait to get it home to get any work done. But good mechanics are where you find them...they can be in your home town or in Timbuktu. Good luck!

[bcbowers]

Sam, my '03 has the temperature gauge included with the tachometer gauge and I assume yours is also. If your temperature gauge is still working then you should be able to adequately protect the engine. If not, then the previous post is accurate in saying "be careful" when climbing hills. I suggest avoiding the cruise control and manually select a lower gear.

Once I start up a hill I typically downshift into 5th gear to maintain speed & help keep the engine cool. As a rule, if your cruise control isn't able to maintain speed then you're overloading the engine which results in the temperature building. You should immediately turn off cruise control and shift into 4th gear if it slows below 50 MPH or so and DO NOT keep the accelerator pedal buried to the floor. I'm sure others will provide some good suggestions.

[Mike & Mike]

Hi Sam!

As with any electrical glitch in the Alpine, the first thing you ought to do is to turn off both battery disconnects: one for the Chassis and one for the House. One is in the battery compartment and the other is on your right as you go up the stairs into the coach (assuming a front door model). Turn them off for one minute and then back on. That resets lots of things.

If that doesn't help, another way of getting RPM info is from the "Diagnostic Port". This is located in front of the passenger seat and behind the kick panel which is velcro'ed in place. There is another in the battery compartment but this won't help for my next suggestion: You could think about buying a ScanGauge "D". The "D" is for "diesel". It plugs into your diagnostic port and reads many parameters. You get to choose 4 for it to read all the time and you can change which 4 anytime you want. Take a look at: ScanGauge - Trip Computer + Digitial Gauges + ScanTools and click on the "D" model. Amazon can get you one in 1 or 2 days. On Amazon, search scangauged.

I own one and it plugged right in. I typically monitor water temp and fuel mileage info. It has one dual ended connector, one for 6 pins and one for 9 pins. It'll plug right into your 2004 Alpine with 400 Cummins.

I found that the cord wasn't long enough and bought an extension cord and a connector. It's a regular networking cable (Cat 6 ethernet cable-also available at Amazon).

That would be a quick and dirty fix to get you the RPM info uyntil you get home, and a neat gizmo to fiddle with later on also.

Cheers!