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Ignition Switch Short?

October 10, 2019, 06:18:15 pm

We're on a road trip on the Washington coast and are having a bit of a problem with the ignition switch. Here are the symptoms when the switch is in the "on" position:
-I can hear the solenoid engage and the engine will start, but no gages or vacuum pump (not sure what it does, but I've always heard it when the switch is on).
-jiggling the switch will engage the gages, but not the pump
-trying to turn the HWH leveling system master switch on makes the gages turn off, which means I have no leveling system.

I was able to retract the jacks this morning after a frantic bout of cursing and persistence, and we can live without them for the rest of the trip, but I'd really like to fix the problem before getting stuck somewhere.

My manual says it's a Chevy switch, which I'll try to find and replace when we get to a city, but is that too simple a fix? Any suggestions?

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Re: Ignition Switch Short?

Reply #1 – October 10, 2019, 06:55:33 pm

Update. Two new clues and an old one:
-Using the spare key gets the gages to work every time. No more jiggling.
-Now when I turn the key to the "on" position) and I turn on the HWH master switch, the gages still turn off (and the master switch does not turn on). But if I leave the ignition switch on for a few minutes the gages turn back on. This suggests to me that the master switch is shorting out and blowing a circuit breaker.

The old clue is that sometimes, very rarely, the HWH master switch will turn on and not result in turning the gages off. So where could the short be?

One last thing, the vacuum pump never turns on. 

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Re: Ignition Switch Short?

Reply #2 – October 10, 2019, 07:05:40 pm

Check for 12 VDC to the IGNITION SOLENOID (under front left of dash).

Then, check for 12 VDC to vacuum pump which is powered by the ignition solenoid through a fuse (same location).

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Re: Ignition Switch Short?

Reply #3 – October 10, 2019, 07:08:24 pm

This may be a long shot, however, do you have a start switch on the engine? If the switch on the engine gets corroded, it can cause the symptoms you are describing.

It may be worth checking.

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Re: Ignition Switch Short?

Reply #4 – October 10, 2019, 07:09:30 pm

Might as well just replace the ignition switch first. Here are the detailed instructions from Barry Beam's site: ignition switch

Good time to also replace the ignition solenoid: Solenoid

The ignition switch is cheap. I'd just buy the whole unit with a new key. You can pick them up at any auto parts store.
jor

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Re: Ignition Switch Short?

Reply #5 – October 10, 2019, 09:53:43 pm

Thanks for the advice. I checked solenoid, and it's getting 12volts. The vacuum pump is getting power to the relay, but not to the pump. I guess that failure was coincidental. What's the pump for anyway?

I don't have start switch, but I will go ahead and replace the ignition switch and solenoid tomorrow. Same with the relay if I can find one. Hopefully that'll get the levelers back on line, we've really come to rely on them.

Thanks again everyone. This forum is an incredible resource!

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Re: Ignition Switch Short?

Reply #6 – October 10, 2019, 09:59:22 pm

The vacuum pump is to power the dash HVAC system.

It is normally powered by a fuse powered by the ignition solenoid (i.e. would only work with the  ignition on).  So, very unusual that it has power with the ignition solenoid inoperative.

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Re: Ignition Switch Short?

Reply #7 – October 11, 2019, 09:56:41 am

Thanks Brett, that explains why the dash heater was acting up on our drive up here. Sorry if I wasn't clear, but the ignition solenoid is indeed working fine. At this point it's looking like the ignition switch must be the culprit.

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Re: Ignition Switch Short?

Reply #8 – October 15, 2019, 02:16:15 pm

Update: The new ignition switch did not fix the problem. I've got an ignition solenoid on order and will put it in today. Further testing found that it sometimes clicks when the ignition switch is on, but  doesn't open the circuit. That explains the intermittent gages and dash lights not working.

I've still got a problem with the leveling system sometimes "shorting" out when I turn on the master switch. I use quotations because I don't know for sure it's a short, only that flipping the switch causes multiple other failures (gages, dash lights, tv relay, maybe others I haven't found), which I can fix by turning the ignition switch off and back on. I'm hoping this doesn't mean a new leveling system is in our future.

The vacuum pump is also still not working when the ignition switch is on. Ever. I can't say for certain when it stopped working, only that I noticed it when the leveling failure occurred. Three simultaneous failures seem unlikely, but I know now there were at least two (solenoid and other).

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