Instrument cut-out, temporary

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Instrument cut-out, temporary

November 23, 2017, 04:30:21 pm

A couple times this past summer I had the unnerving experience of having (almost all) the dash instruments cut out. Only air pressure remains (for obvious reasons). The first instance of this issue was noticing that the speedometer did its usual left-to-right swing from full off to full on - just as it does every time the ignition is switched on (in the warm-up phase) just before advancing the key to the second position to engage the starter and start the engine. The surprise came when this happened while I was driving down the highway - the engine continued to purr along, but the instrument loss was only long enough for a WTF moment. It has happened other times later, sometimes lasting for several minutes and during which, the engine still runs although I can't see any reading on speed, revs, oil pressure, battery function, etc. [All the electrical gauges of the dash).
One other indicator that this may be an ignition solenoid issue is that sometimes (engine off) when I try to start the engine there is no response whatsoever. After a few attempts (key on, key off, key on... etc.) I get the expected speedo swing and usual low-pressure alarm bell, and then the starter can be activated.
I have searched under instrument failure, etc. but not found this exact problem.
My possible targets for further investigation are the starter solenoid, and the ignition switch itself. Our GV is a 1993, so there may be some issue with a worn receiver for the ignition key.
Any ideas about diagnosing whether or not I have an erratic solenoid, since once the engine is running this loss of instruments (and signal lights!) can happen when we are rolling down the highway.

Re: Instrument cut-out, temporary

Reply #1 – November 23, 2017, 05:28:06 pm

Quote from: Mike_Sandra_Lloyd – November 23, 2017, 04:30:21 pm

My possible targets for further investigation are the starter solenoid, and the ignition switch itself.

I think you mean the ignition solenoid, rather than the starter solenoid. Ignition solenoid is under the front dash cover - starter solenoid is at the back end of the coach.

I think you are on the right track. Sounds like a intermittent connection to me, since it comes and goes at random. The ignition switch could be at fault, or the red wire going from the ignition switch to the ignition solenoid. If the current flow is interrupted by either of these items, then the ignition solenoid could open/close rapidly and cause the symptoms you describe. OR, the ignition solenoid itself could be acting up.

I would normally suggest checking for a bad ground, but in this case the engine panel instruments all have individual ground wires, so having all of them go bad simultaneously would be unlikely.

Intermittent wiring faults are the worst type of electrical problem, because they are so often hard to reproduce in the shop.

With the engine running, wiggle the wires around that are attached to the back of the ignition switch. See if the fault occurs. Also move/shake both ends of the red wire from ignition switch to ignition solenoid. Hopefully, something will trigger the fault, and then you can correct it. If that doesn't work, go to next step.

You have three solenoids on your coach: ignition, aux start, and boost. If the same model/type solenoid is being used in all three places on your coach (this is not unusual), then you could swap the ignition solenoid for one of the other two. See if that makes your problem go away. If so, replace the bad solenoid.

Good luck. Let us know what you find.

Re: Instrument cut-out, temporary

Reply #2 – November 23, 2017, 05:48:29 pm

Easy to troubleshoot.

Next time this happens, pull to a safe place, but do NOT turn off the engine.

Open the dash. On the far left side under the flip up dash is the GROUND CONNECTIONS. The IGNITION SOLENOID is about 8" to the right and a little aft. One large lug reads chassis battery voltage. The other should read exactly the same voltage when the ignition is on.

In addition to gauges, a sure fire diagnostic that the ignition solenoid is not working is that the dash HVAC fan quits at the same time.

Re: Instrument cut-out, temporary

Reply #3 – November 23, 2017, 05:51:51 pm

I had the same indications, no power to the instrumentation and no start. Never had engine running with no instrumentation. I replaced ignition solenoid, and problem went for a while, then returned. Is there a resistor wired into the solenoid?. If so disconnnect and see what happens. There is a discussion about that here somewhere, but it seemed to have solved my problem. I also replaced and rebuilt the remote starter and battery tie solenoids along with associated relays and circuit breakers which were in terrible shape and haven't had any problems since.
Mike

Re: Instrument cut-out, temporary

Reply #4 – November 23, 2017, 09:13:05 pm

I had your exact symptoms it was the ignition solenoid. Alarming the first time it happened and always came back on before I could test it. Once it decided to keep the bus from starting that was a tense five minutes accompanied by DW questioning every move.

Re: Instrument cut-out, temporary

Reply #5 – November 24, 2017, 08:28:59 pm

Maybe just loose nuts on ignition solenoid. But it doesn't hurt to carry a spare.

Re: Instrument cut-out, temporary

Reply #6 – November 24, 2017, 08:40:24 pm

You might check the battery connections and battery switch for a bad connection.

wantabe

Re: Instrument cut-out, temporary

Reply #7 – November 25, 2017, 12:19:23 am

Thanks all for the input. The search begins! Wolfe10, now that you mention it I do remember that the fan did cut out/cut in as well. I have checked for loose wires under the dash but I will focus attention on the ignition solenoid for a first step. I will keep in touch.

Re: Instrument cut-out, temporary

Reply #8 – November 25, 2017, 09:05:59 am

Yes, when the ignition solenoid fails, anything powered only when the ignition is on FAIL. Be aware that a defective ignition switch will give the same symptoms, but failure of the solenoid is much more common.

Many of us have replaced the ignition solenoid with this electronic switch: L Solenoid - 12/24V DC 250A - Blue Sea Systems

Yes, more expensive, but look at the specs!

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Instrument cut-out, temporary

November 23, 2017, 04:30:21 pm

Re: Instrument cut-out, temporary

Reply #1 – November 23, 2017, 05:28:06 pm

Re: Instrument cut-out, temporary

Reply #2 – November 23, 2017, 05:48:29 pm

Re: Instrument cut-out, temporary

Reply #3 – November 23, 2017, 05:51:51 pm

Re: Instrument cut-out, temporary

Reply #4 – November 23, 2017, 09:13:05 pm

Re: Instrument cut-out, temporary

Reply #5 – November 24, 2017, 08:28:59 pm

Re: Instrument cut-out, temporary

Reply #6 – November 24, 2017, 08:40:24 pm

Re: Instrument cut-out, temporary

Reply #7 – November 25, 2017, 12:19:23 am

Re: Instrument cut-out, temporary

Reply #8 – November 25, 2017, 09:05:59 am

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