start procedure gone south

[garhawk]

Hey All,

My bus won't start - conventionaly, that is.

First off, it is a 1989 Model 20 NJT with a DD Series 60.

The normal start procedure was: a) turn on Master Switch  b) wait 6 to 8 seconds and push the start button.  On occasion, that procedure would malfunction requiring a jump-start across the relay inside the rear engine compartment.

Yesterday, that procedure went south for good.  The only way to start the engine is through the start relay at rear.  Along with the front panel start being in denial, there is no longer power to the cruise control, (and just when I had a solution to getting the cruise control to cruise).

There is power on the incoming lead at the start switch and, when closed, power transfers to the outgoing lead.  Seems the problem lies between the start switch and the start relay in the rear. 

Anyone have an idea?

[fe2_o3]

Neutral safety switch? Most have to be in neutral to start. The neutral safety switch is a good place to start I would think..Then follow the electricity till it stops..Good luck...Cable

[white-eagle]

Cable is right, it does have to be in neutral to start, but that also cuts the rear start button out.  Nothing works if its in neutral or if you have the rear "off" switch in the "off" position.
you said you almost have the cruise working again?  does that mean you had the dash apart?  if it does mean you were in there fiddling around, i would recheck connections.  my start switch occasionally seems to not make good contact, but a second hit always works when that happens.  mine is probably like yours.  i have an electric toggle that turns on the electric so that when the air builds to 15 or so, it doesn't shut the engine back down.  then i have a momentary toggle that actually turns the starter to start the engine, similar to the button push in the back.  i guess i'd make sure the momentary toggle in front works well and makes good contact on its wires.
hth.

[PCC]

Is there also an oil pressure sensing switch that makes sure the starter cannot be activated while there is oil pressure? If that switch goes open, it would mess up your start request.

PCC

[luvrbus]

That bus having  had a air starter and being re powered from a 6v92 with a 60 series I bet it is not going to be your standard bus wiring it's going be Custom wiring by PO lol no telling how it is wired ,and to add insult to you NJT Eagles were all white wiring

good luck Gary

[garhawk]

Yep, batteries are in good health.

Have cleaned all grounds which should matter. Left some others for another un-hurried time.

As mentioned in my original post, the 12v lead into the start switch is hot. When the switch is closed, the outgoing lead becomes energized. Conclusion: switch good and power sent to rear panel solenoid through whatever devices NJT or PO devised.

Because of the 6 to 8 second delay in the start switch (from touch to starter) it seems to me that the circuit travels through a time-delay device of some sort. If so, what do you think that animal resembles and, where would it most likely reside?

Go to rear panel and energize the small power lead on the solenoid from some extraneous source and, bus starts right up. Does that rule out the alternator?

Yes, the NJT bus was originally an air starter and I have the two major wiring diagrams. (little does it do me to attempt reading them - it's a whole lot like spilled spaghetti). Yes again, all (except for some after wiring via later technicians) wires are white with numbers. It has not been overly difficult to find and decifer the numbers however, it is extremely difficult to follow their routes through all the combined/closed wiring looms.

Please stay with me guys, I need all the help available. If you have further thoughts based on this last bit of information, they will be appreciated. I'll keep you posted as to progress and, hopefully a final solution!

[garhawk]

OK Guys,

We have the start procedure on a 0 degree heading with all systems GO!

After having run the start circuit from front to back with no success, I decided to begin at the rear start switch and work forward.  Using the suggestion from some of you, I moved the rear start switch from front to rear and back to front again.  Just for giggles, tried the front panel start switch and, sure enough, the engine fired.  Tried the same procedure again and no such luck - everything dead once more.  Removed the rear start switch panel and found a pinched and bare wire from some previous removal and reinstallation - problem solved!

Now we have normal start procedure, jakes, cruise back on and, all systems seem to behave properly. 

After repairing the rear start switch wiring, I decided to crawl underneath and ground the G2 wire from the ECM.  Eric Brown had received the advice from a local truck dealer source to begin the healing process for our cruise controls on the DD S60s. 

A quick trip out the by-pass proved the advice from the trucker is sound - that is one solid cruise control.  The needle appeared to be glued to the speedometer glass @ 55 mph with no more than 15 rpm movement in the tachometer.  All that's left is to relay a tap into the brake lights for cancellation.

There's even more good news.  During the process of trying different combinations of start procedures, I stumbled across a set of relays wherein lies the elusive time-delay.  Didn't nail it down just yet, but will as soon as I have the wife handy to operate the switches while I feel for the little bugger. 

Thanks to all of you who responded. Steve, that was a really kind offer to come over and help.  You don't know how close I was to calling.  Eric, maybe we should throw in together and buy the trucker a nice dinner.  Clifford, you're right - if you find a wire other than white on an NJT 20, it's an add-on or repair.  Pete, what can I say, your tops!