Help me figure out wiring?

[EastCoastCB]

Originally Posted by BlackJohn

Bang on dan-fox. parts didn't magically help so being the source hasn't been discovered, time for a rip out and rewire. Agree very much that this is a harness issue now but not being there won't help these boys. Maybe the two of them can track the source down.
Unbelievable how this got complicated to the point of frustration.
One bad termination of a wire or mistaken termination or sounds like a diode in the wrong position blocking voltage therefore no reading as chris was looking at.

We eliminated the diodes, that much I'm sure of.

[EastCoastCB]

Both motors have been demonstrated to work properly, just not both of them at the same time. Either the right motor or left motor will stay on depending on which one is wired as wiper 1 and which is wiper 2. I have three switches, and three motors. I'll have Chris test them all individually but I'd bet they're all good.
All this electrical funkiness HAS to be coming from the wiring or the nest under the outside panel. That much I'm fairly sure of. But what do I know!?

[PNW_Steve]

Originally Posted by EastCoastCB

Both motors have been demonstrated to work properly, just not both of them at the same time. Either the right motor or left motor will stay on depending on which one is wired as wiper 1 and which is wiper 2. I have three switches, and three motors. I'll have Chris test them all individually but I'd bet they're all good.
All this electrical funkiness HAS to be coming from the wiring or the nest under the outside panel. That much I'm fairly sure of. But what do I know!?

When I went to school we were taught two key concepts that are core to troubleshooting electronics/electrical issues:

FM and Magic Smoke

All devices rely on FM to operate.

All devices come from the factory with Magic Smoke sealed inside.

When a device fails you will generally find that the Magic Smoke has escaped or that the FM is simply AFU. Sometimes both.

Early on I did not believe in the Magic Smoke but after several first hand observations I am a believer! Let the smoke out and the device fails.

FM ( fu[king magic) is a little harder to prove..... But when the FM is AFU things go to hell...




Seriously,

It sounds like you have clearly eliminated the motors as the issue. If I am following along it sounds like you have a plan to check all of the switches as well. Hope you find something there. If not it looks like a wiring fault.

Good luck Guys.

[EastCoastCB]

Yeah, as far as I can tell we've not released the magic smoke yet, thank goodness.

[Robin97396]

Just a dumb thought that you might have already done. Have you gone to a bus barn to talk to a mech. I've seen these issues before, and that's probably why they dumped that bus. A bus mech would likely have seen this issue previously and might be able to make a few suggestions to check before you tear out the harness.

[cadillackid]

Originally Posted by PNW_Steve

I worked for many years repairing various equipment. More than a few times I got stumped when I suspected a particular part was bad so I replaced it with a new part and the problem was not resolved. I made the assumption that the part I replaced was not the problem. Then got stumped because the symptoms indicated that it was that part.

After much tail chasing I found that I had replaced an old failed part with a brand new failed part.

Odds are against it but it does happen from time to time.

Just a thought....

ive had this happen too.. its not the first thing I suspect but also not something I totally discount either...

the advantage here is we have 3 Busses... the wipers work on 2, not on one... lots of reference to go on..

-Christopher

[DoubleO7]

Maybe the new wiper motor was such a good price because it was dead on arrival to previous customer.

EC....did you ever try switching switches to see if the problem followed the switch?
Did you ever swap the motors to see if the problem followed the motor?
You already have another set of batteries in your other bus. Have you swaped the batteries to see if the problem is still there?

[Robin97396]

I'd expect the switches to be the same so interchanging would be possible for testing. Weren't the motors left and right side units?

[cadillackid]

the motors are universal.. the sweep is controlled by the attached mechanism.. and the motors are installed in the same orientation left and right side it looks like...

I'll double check on that when im up there, but all of the ones i could find in school bus parts catalogs dont specify right and left.. at least not for these years and bus.
-Christopher

[BlackJohn]

For anyone interested still...

I searched for a schematic for wiper switches of this sort.

What I found will explain the switch operation for most and is something for chris to use tomorrow for comparison sake.

Search for 1978 Chevy Wiper Diagram1.jpg

Anyway, Chevy or not, it is generic to all basic wipers, but no intermittent.

No biggie there, that is done in the newer switches.

chris you will see the washer pump coil inside that switch. That should explain the diode situation, Kinda does to me depending where they connected the diode and hopefully not soldered in backwards. Just ring it all out I guess to understand it. Good luck tomorrow boys.

I can't post pics here yet so anyone who can't find the link, email me your address and name hereon skoolie and I'll send you a copy.

[BlackJohn]

Good question Robin. Think mine are as they sweep opposite but no batteries in my bus right now to check, dag nab it!

[BlackJohn]

Originally Posted by PNW_Steve

When I went to school we were taught two key concepts that are core to troubleshooting electronics/electrical issues:

FM and Magic Smoke

All devices rely on FM to operate.

All devices come from the factory with Magic Smoke sealed inside.

When a device fails you will generally find that the Magic Smoke has escaped or that the FM is simply AFU. Sometimes both.

Early on I did not believe in the Magic Smoke but after several first hand observations I am a believer! Let the smoke out and the device fails.

FM ( fu[king magic) is a little harder to prove..... But when the FM is AFU things go to hell...




Seriously,

It sounds like you have clearly eliminated the motors as the issue. If I am following along it sounds like you have a plan to check all of the switches as well. Hope you find something there. If not it looks like a wiring fault.

Good luck Guys.

FMe! That was funny PNW,

[cadillackid]

wewrent we just talkin last week EC about keepin the smoke INSIDE the devices and not OUT? or was it that theres more than one kind of Magic Smoke...
-Christopher

[EastCoastCB]

Originally Posted by Robin97396

Just a dumb thought that you might have already done. Have you gone to a bus barn to talk to a mech. I've seen these issues before, and that's probably why they dumped that bus. A bus mech would likely have seen this issue previously and might be able to make a few suggestions to check before you tear out the harness.

They put new tires on ten of them then sold em all a year later. It was simply retired due to age/replacement.

I'm starting to lean heavily to the problem being related to the removal of the monitor/security/school stuff.

GLAD to have such a great bunch of folks to help me out, yall are the BEST.

[EastCoastCB]

Originally Posted by DoubleO7

Maybe the new wiper motor was such a good price because it was dead on arrival to previous customer.

EC....did you ever try switching switches to see if the problem followed the switch?
Did you ever swap the motors to see if the problem followed the motor?
You already have another set of batteries in your other bus. Have you swaped the batteries to see if the problem is still there?

The new wiper wasn't really a "good" price. I paid full retail for the exact oem part.
The problem doesn't follow the motor. I checked. It certainly is NOT either wiper motor. I have an extra spare motor now. No biggie. I have two buses. So far.

[Robin97396]

Hey ECCB, look how much more you know about electronics now than you did a couple weeks ago.

[EastCoastCB]

Originally Posted by Robin97396

Hey ECCB, look how much more you know about electronics now than you did a couple weeks ago.

LOL right.

[DoubleO7]

Way back to you o.p.
The white wire near the lower left corner of access door you finger is on or near.....
Looks like maybe the door cut it. Looks mangled and not a cut- - on purpose cut.???
Maybe look and see what it might have gone to/from?

[EastCoastCB]

Originally Posted by DoubleO7

Way back to you o.p.
The white wire near the lower left corner of access door you finger is on or near.....
Looks like maybe the door cut it. Looks mangled and not a cut- - on purpose cut.???
Maybe look and see what it might have gone to/from?

It went to the video monitoring system. comes from the alternator and is cut several times. They definitely did cut it and did about every three feet or so.

[cadillackid]

is that the one we yanked out?
-Christopher