Dash gauge problems

[trabuco]

Need some help and ideas on two dash gauge problems.

Problem #1 boost gauge: gauge has completely stopped working. I'm still generating boost but the gauge is registering zero. A few weeks ago the gauge became flaky and recently stopped working all together. This is a stand alone gauge on my dash panel.

Problem #2 engine temp gauge needle is all over the place: the gauge will start out reading normally and then start moving rapidly back and forth between 100 and the run temp. No Rhyme or reason when this happens. Then the gauge will read normal operating temp for an hour or so and the will act up again. This gauge is part of a larger gauge with fuel and trans temp and they are working correctly.

Checked all connections on the back of the gauge and all are tight. Sending unit for the temp gauge is good.

Any help would be appreciated.

[Bowiesmom]

I wonder if its the sensor?

[Vanwill]

I am not sure about your year model, but earlier models had a totally mechanical boost gauge. There was a tube that brought the pressure from the intake system all the way to the instrument cluster. If your gage is not working, check to see if it is mechanical, i.e. has a plastic tube connected to its back. If it does, you most likely have a leak in the tubing. Look for where it originates at your engine.

For instruments in general, the most common cause of gage malfunctions is poor grounding. Most specifically, there are ground buss bars located at several points on your coach. They are identified by being aluminum bars that have many white wires attached to them. Spray the bars liberally with WD-40, loosen and re-tighten the screws. You will almost surely find several of them to be loose.

[trabuco]

vanwill,

I neglected to mention the boost gauge is mechanical. I will check the engine end and see if it has a possible leak. The dash end is ok.

I'll start looking for the grounding buss bars and do as you suggested.

Thanks

[djhinds]

My boost gauge would act very slow, slow to read boost and slow to return to 0 with no boost. I removed the fitting on the intake manifold where the yellow air line connects and found it plugged with carbon. There is a small piece in the fitting covered with carbon so I used carb cleaner to clean it. It did not cleanup very good so I used a very small numbered drill bit and drilled a hole in it. The hole should not hurt anything as there is no flow of air only pressure to the gauge. My gauge works instantly now, that was 20,000 miles ago. Push in on the air line then hold the ring in then pull the air line out, to install air line make sure it is clean then just push it in the fitting all the way.
I tightened ALL the grounds on the gauges (white wire) and found a grounding bar under the pass side dash and tightened them also. Everything works smooth now....

Hope this helps....
Dave

[trabuco]

Dave!

Based on the what you described with you boost gauge I may have the very same issue. I will check it when I'm back off our most recent trip. The grounding issue might be a little tuffer to find.

Appreciate the help!

[YC1]

My buddy has been having guage troubles in his for several months. All over the place and erratic. I suggested he follow the wires to clean the grounds and he did the best he could I guess. He decided to give the Scanguage a try and after a bit of effort to find the real port to plug it in he has it up and running. Seems his dash gauges are working fine now too so I suspect he managed to wiggle some connections.

[DtBt]

When my engine temperature gauge became erratic on my Windsor ISC it turned out to be the connection at the temperature sensor. The sensor on your ISL should be located under the engine exhaust manifold rear (toward MH front). To be clear it is accessible from underneath of the Drivers side. There should be two blade connectors. On mine the connectors were vibrated and cooked to death. I used new heat shrink crimp-on connectors, Ancor I believe, to give a better strain relief.