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Bad octal relay socket – sneaky failure!
Big win today in my gremlin chasing. I had an intermittent condition where I couldn’t start the bus from the front. The rear start switch didn’t work either, but I was slow to realize this because a previous owner had installed a second rear start switch below the factory switch which simply bypassed the starter solenoid and ran power through the new switch. (See the grossly-undersized yellow wires from the solenoid in the photo below.) This new switch effectively bypassed the starter relay, cutting the parking brake switch and neutral switch out of the loop. I initially thought this was normal, but soon realized it was installed to work around this intermittent issue. Ever start your bus from outside while it’s stuck in gear? Yikes.
Another clue was the previous addition of a “neutral” toggle switch next to the shift selector. Clearly, this was an attempt to deal with the same issue. When I first bought the bus, the shifter had an issue where after a while it would only shift in the direction of low gear, not toward a higher gear, neutral, or reverse. I got stuck in a few bad spots until I figured it out. Not having reverse really sucks. That’s a separate issue (solved by replacing a hydraulic pilot valve at the Bennett shifter), but it led me to believe the “neutral” toggle switch was to allow you to start the bus in gear. Someone was treating the symptom instead of the illness.
Long story short (too late), I realized that my intermittent fast idle might be related. Much digging through whatever schematics I could find led to the Starter Solenoid Relay, also labeled as the Starter Interlock, as a possible culprit. I swapped the “ice cube” 8-pin relay with another one, but no luck. Back to head scratching. Then my marker lights quit. When I pulled that relay, I could see a damaged tab on the octal relay socket, breaking the circuit. Further inspection showed that 35 years and the heat of the engine compartment had damaged a few of them, including the Starter Solenoid Relay. You couldn’t see the damage unless you removed the screw at the tab.
I’ve been trying to figure this one out for more than three years, and have had a few shops take a stab at it, too. In fairness, I waived them all off pretty quickly rather than pay the shop rate for deeper investigation. Having shops chase that shifter problem nearly broke me, and I eventually fixed it myself after finding a guy that helped design the Bennett shifter.
So, keep the sockets in mind if you run into a relay problem that comes and goes. They’re about $5 each.
1984 96" with 8V92TA
(remodeled Liberty Coach)
Greenwood, MO -
5 Replies
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Good job tracking down the problem Chad, it’s amazing how people go to such length for a cheap work around.
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Great story Chad.
Great point Tom. Sadly the world is full of people like that and they are not just previous Prevost owners! Anyone involved in home remodeling, plumbing, electrical, or HVAC can horror story after horror story.
I’ve known a few of these re-engineering geniuses over the years. They are typically well intentioned, take pride in solving problems by themselves, and in some cases take more pride in doing it on the cheap.
One might call them “hillbilly engineers” or “backyard mechanics”. But I’ve known both “hillbilly engineers” and “backyard mechanics” to the group them with these hackjob guys is disingenuous and unfair.
Nothing beats someone who has great diagnostic skills. I don’t know how much of that can be taught. I was fortunate to work with some great diagnosticians in the airplane at a young age.
Glad to see Chad has solved nagging his problem. I wonder if a certain previous owner hasn’t left him with other challenges.
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I am anal about logging work I do on the coach. I have many minor changes I have made to my coach, such as adding a solenoid valve and thermostat to limit water heated by coolant (which can reach over 200 degrees) so I stop coolant flow when the water in the HW tank is at 125 which is what the factory thermostat setting is.
I have added more lights to the engine compartment.
I have added multiple key off circuits for my dash cams, GPS and Pressure Pro. But every change has been logged, detailed and information about how to restore the coach to the way the factory built it is included.
What Chad experienced is inexcusable. If an owner cannot afford to make repairs properly, or take the time to make subsequent owners aware of the changes they should not own a coach. Mickey Mouse repairs are often dangerous, poorly done, and an indication the person doing the repair shouldn’t be allowed to own tools.
Chad is a pilot and I think aircraft owner and I am certain he demands work on his plane is properly logged and done to the required quality level. We should expect nothing less on our coaches.
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There have certainly been other headaches, but after three years I have things mostly in great shape. I actually traded my last airplane for this bus, so the previous owner was a pilot and also an A&P, IA. I’m going to assume that he wasn’t the one who did this crap!
The best part of these projects is that I add so much to my own understanding of the systems. I take a lot of notes as I go, tracing wires and drawing circuits. The Prevost diagrams are usually close, but I don’t have anything from Liberty showing changes they made. Additionally, mine was one of the last 96” coaches, so many of my systems are the same as the 102” XL in later years. I almost never have access to a correct diagram or schematic, and have to piece it together from what’s available.
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As a proud Ozark Hillbilly, I never mess with anything an engineer spent hours designing and testing. There are other ways for being a Hillbilly, like talking about “thedamngovernt”.
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