No Tach, Speedometer and No alternator

[Luther Taylor]

MotorHome parked for 6 weeks at our lake spot. Got ready to leave today and it started right up but those gauges didn’t not work. Drove it home about 40miles had wife drive ahead of me so I could tell my speed. 

Everything else seemed to be okay.

If the alternator is not producing voltage will it affect those gauges. I’m thinking 🤔 it could. 
Any help would be appreciated. Thanks in advance. 

[Ivan K]

In that era they used alternator pulses for RPM but hardly for speed since that involves gears so not sure now about how that might be related.

[Tom Cherry]

1 hour ago, Luther Taylor said:

MotorHome parked for 6 weeks at our lake spot. Got ready to leave today and it started right up but those gauges didn’t not work. Drove it home about 40miles had wife drive ahead of me so I could tell my speed. 

Everything else seemed to be okay.

If the alternator is not producing voltage will it affect those gauges. I’m thinking 🤔 it could. 
Any help would be appreciated. Thanks in advance. 

I’d pull loose the wiring going to each of the “non functional” gauges….and if the  pigtails were pugged in on the other end….them too,  reseat them.  Check where the gauge or dash ground bar or terminal strip is.  There is s main “instrument” or dash cluster or entire “dash” ground going to a chassis ground stud up front.  Find it….pull it…clean it.  Typically, there is a MAIN harness that goes into ONE “cluster” or big gauge and the other gauges run off that.  Loose connections or even hungry mice or squirrels have been known to shut down things.

Do some exploring….then see how that changes things.  As Ivan says…the Tach usually gets s signal..but eventually, the ECM took over…don’t know about yours.

I’d flagging for @Larry Laursen.  He is an expert on your “of that vintage” MH.  Maybe he can chime in?

NOW…when you say “alternator”, what did you use for criteria?  Did you put  a VOM on the chassis batteries and measure the charging voltage…should be in the high 13’s.  If it is that, then you may have a “control” issue.  The “of that era” alternators were notorious for driving folks crazy and really working just fine.  They just like to cry WOLF

[Gary 05 AMB DST]

Silverleaf may be the easiest solution.

Gary 05 AMB DST

[cbr046]

Just the tach and speedo or are there more?  Which gauges, specifically, don't work? 

You can use a GPS to check your speed . . . . . there's even some phone apps that will read speed.

- bob

[Luther Taylor]

3 hours ago, cbr046 said:

Just the tach and speedo or are there more?  Which gauges, specifically, don't work? 

You can use a GPS to check your speed . . . . . there's even some phone apps that will read speed.

- bob

 

Those and the Alternator gauge. Engine temp gauge ready is lower than normal. 

[cbr046]

If I turn on my headlights my alt gauge goes down to ~10V but normal through other gauges, oil goes to 0 psi . . . . but if the light behind the oil gauge flickers it reads normal.  In my case it's not the system . . . . probably bad ground. 

I'd venture a guess your issue is something common, like bad ground, bad ignition switch, bad day . . . someone mentioned jiggling wires / wire harness while watching the gauges.  That'd be a good start.

Try jiggling wires / harness with ignition on but not running and watching the alt gauge.  That would save irritating the neighbors. 

- bob

Edited August 16, 2023 by cbr046

[Tom Cherry]

2 minutes ago, cbr046 said:

If I turn on my headlights my alt gauge goes down to ~10V but normal through other gauges, oil goes to 0 psi . . . . but if the light behind the oil gauge flickers it reads normal.  In my case it's not the system . . . . probably bad ground. 

I'd venture a guess your issue is something common, like bad ground, bad ignition switch, bad day . . . someone mentioned jiggling wires / wire harness while watching the gauges.  That'd be a good start.

- bob

Some say an ignition switch.  As old as yours, maybe.  The way you test is to keep “playing” with the ignition switch on snd off…not starting.  Wiggle or jiggle or push the key in many directions.  If you get erratic or different “lights” or such…then a new switch.  Typically less than $75 and common.  PN is in Parts list file.

YES…a good many simple things….before you go crazy and start messing with individual gauges or buying stuff without knowing what the real issue is.

21 minutes ago, Luther Taylor said:

 

Those and the Alternator gauge. Engine temp gauge ready is lower than normal. 

When you say “alternator”, assume you mean the Voltage readout and NOT an Ammeter showing Amps.  Put a VOM on the chassis battery when running after 5 minutes or so.  Do that first and post a picture of the gauges.  Right now, many may be guessing….need to get specific…

[clkimmel]

14 hours ago, Gary 05 AMB DST said:

Silverleaf may be the easiest solution.

Gary 05 AMB DST

Silverleaf only has the glass dashboard replacements now, they no longer sell the VMSpc version.

[hitechpete]

19 hours ago, cbr046 said:

If I turn on my headlights my alt gauge goes down to ~10V but normal through other gauges, oil goes to 0 psi . . . . but if the light behind the oil gauge flickers it reads normal.  In my case it's not the system . . . . probably bad ground. 

I'd venture a guess your issue is something common, like bad ground, bad ignition switch, bad day . . . someone mentioned jiggling wires / wire harness while watching the gauges.  That'd be a good start.

Try jiggling wires / harness with ignition on but not running and watching the alt gauge.  That would save irritating the neighbors. 

- bob

I had a similar issue with my 2000 Diplomat, gauges changed readings with headlights on/off, speedometer erratic voltmeter wrong etc. I clipped a known good earth onto the back of each gauge in turn, then wired a new earth to the last place it made any difference to readings. It also fixed my very erratic step cover.

[Gary Cole]

I installed a 24 point terminal strip, listed for stranded conductors, under the dash with a dedicated 10 ga conductor from the main ground lug located in the FR bay. Most everything now has a separate ground wire. Probably overkill however DC circuits with dedicated grounds which are labeled with their corresponding circuit,fuse number, and  located at a known common grounding terminal make trouble shooting much easier.

Edited August 17, 2023 by Gary Cole

[Luther Taylor]

Update on this. I had a Master ASE Technician come out and check and diagnosis the problem. He checked everything and apparently there is and open connection somewhere in the system. He found fecal matter from what is either from a rat or pack rat. Pack rats are notorious for chewing up wiring. 
We contacted our insurance company and under Comprehensive we are covered. A claim has been filed. The adjuster called and they are going to send someone to check. So we shall see. Thanks to everyone for their input on this it is appreciated. Will let you know the outcome. 
 

[Tom Cherry]

3 hours ago, Luther Taylor said:

Update on this. I had a Master ASE Technician come out and check and diagnosis the problem. He checked everything and apparently there is and open connection somewhere in the system. He found fecal matter from what is either from a rat or pack rat. Pack rats are notorious for chewing up wiring. 
We contacted our insurance company and under Comprehensive we are covered. A claim has been filed. The adjuster called and they are going to send someone to check. So we shall see. Thanks to everyone for their input on this it is appreciated. Will let you know the outcome. 
 

From my first post….Loose connections or even hungry mice or squirrels have been known to shut down things.

A A timothy field mouse had one snack and the bill was over $6,000 on my wife’s 2014 ATS.  Several shorted emission sensors, repairs to (not replaced) harness & TWO new Catalytic converters.  You just made me keep putting “rat baits” inside and in the bays.

Hope it turns out OK.

[Luther Taylor]

This is an update on this. 
Insurance denied our claim said that whatever happened to to wiring couldn’t be  determined. We have not found the problem as of yet. 
So I ordered the Bluefire adapter and installed it in the motorhome. 
IT WORKS GREAT. I have a complete dash now, all the gauges that I want. 
We’ve found someone to work on it but that’s  about a 3hour trip and we could risk driving that  far with no dash. We will take it there when time and money allows. Check out the Bluefire  System. Think you’ll like it.