SOLVED & updated: Any mechanical/electrical genius out there

This is a 1994 Tiffin Allegro Bus 34 foot diesel pusher.

Here's my problem: I am having to turn the key to the start position 10 or 12 times to get the engine to crank or if I hold the key in the start position for 6 or 8 seconds the starter will finally engage. I have already replaced the ignition switch on the steering column (actuated by the key) so the starter switch is good and the symptoms are the same with the old or new switch. The starter solenoid is good, the starter is good and the starter relay is good. I've checked all of the above items using the accepted process of elimination with a 12 volt test light. The problem seems to be the start wire from the starter switch is not making good contact somewhere between the starter switch on the steering column and the starter relay in the back engine compartment.

I've attached a photograph of my fuse panel. I am wonder if the yellow fuse in the panel labeled ign (ignition) might be causing the no crank problem. A couple the fuse slots have melted somewhat and/or has broken pins. I've already found and repaired the cause of the melting. That yellow 20 amp ignition fuse slot does have a broken fuse pin on the left side (this is on the the hard wired part where you insert the fuse and not the fuse itself). The fuse is making contact on that one side fuse legs but it's probably not making ideal contact. Anyone know if that fuse might be the cause of the no crank problem.

I have checked the start wire from the ignition to the starter relay by tracing everything accessible. My goodness what a cluster of wires. I have been unable to locate a problem in that wire anywhere that I've been able to find. Like I said, after holding the switch in the start position or repeatedly hitting the start several times, the engine will crank and run fine. There is no problem with the engine performance after it starts. I know I can wire a momentary switch at the drivers position to the starter relay but I would rather fix it the right way.

I'm open for any suggestions and thanks for any input.

Class A

WyoTraveler
Explorer
Aug 31, 2014
JMHO. I would temporarily by pass the fuse with a jumper and fuse. If it solves the problem most likely the fuse contacts. If not, I would temporarily run a complete wire from ignition. I'm sure you realize if you took it to an electrical repair shop they would most likely just run a new wire from the switch to the solenoid with a new fuse in the line. I had a similar problem with my previous PU. Mice had chewed half way through some of the wires. Easier to replace bad wire than an entire cable.
Victory402
Explorer
Aug 31, 2014
I would like to think there is a relay that brings in your starter solenoid. Might be bad?
rcmiller32
Explorer
Aug 31, 2014
I would look for a large HD starter solenoid between the chassis batteries and the main starter solenoid. Most times this was closer to the batteries and then a heavy cable would run to the starter solenoid. Also check all the battery and solenoid connections closely for corrosion and dirt. Last I would check out for a possible defective neutral safety start switch or relay.
Bikeboy57
Explorer
Aug 31, 2014
Most of us, including me, trace down the hot side of a 12V DC system when troubleshooting. You will need to confirm good grounds on all the relays and solenoids.

You can't do that with a test light. Invest in a voltmeter if you don't have one.

Check ALL Grounds.
midnightsadie
Explorer II
Aug 31, 2014
sounds like burnt contacts ,in a start relay.
darsben
Explorer II
Aug 31, 2014
WyoTraveler wrote:
JMHO. I would temporarily by pass the fuse with a jumper and fuse. If it solves the problem most likely the fuse contacts. If not, I would temporarily run a complete wire from ignition. I'm sure you realize if you took it to an electrical repair shop they would most likely just run a new wire from the switch to the solenoid with a new fuse in the line. I had a similar problem with my previous PU. Mice had chewed half way through some of the wires. Easier to replace bad wire than an entire cable.

X2
Cheap test no real money or time invested. This is a good place to start.
Even if it is not the problem I would run a new wire with an inline fuse. It is a future problem just waiting to bite you on the posterior at an inopportune moment
YC_1
Nomad
Aug 31, 2014
I too would park the test light at this time. You need solid voltage information now. Could easily be a ground. Start right at your starter solenoid. If you have a smaller relay driving the starter solenoid you need to measure voltage on all four terminals or the metal housing if there isn't four terminals. Drag your shoreline cord around and use the ground lead so you will have the same reference while taking any measurements.

One trick on a sloppy fuse holder is to twist the fuse legs a bit.

With all of this my question is do you hear any clunking near the engine area every time you turn the key or only when it decides to engage? If you hear any solenoids clunking and no engine cranking that is where I would start with voltage measurements.
Geocritter
Explorer
Aug 31, 2014
I was having starter problems with my 1994 460 V8 powered Holiday Rambler. The starter barely cranked. I had the starter rebuilt and installed a new 750amp battery and new battery cables but sill no joy, in frustration I purchased a new starter assuming the rebuild was bad, still wouldn't crank worth a flip. I finally went out and purchased a dedicated ground cable for $8 and bolted one end to the frame and the other end to one of the bolts that attached the starter. FINALLY! Problem solved.
Tinstar
Explorer
Sep 01, 2014
I'll check voltages at all the post but from checking yesterday, there will be NO voltage at the S (start) terminal on the start solenoid until after 8 or10 seconds. I crawled from front to back underneath it yesterday and there is no damage to the start wire anywhere along the way. I repaired the damaged 20amp fuse holder and replaced the ignition relay. I cleaned the ground wire connections and the solenoid works as it should or at least it does when 12volts finally reaches the S terminal,,, which takes 10 - 12 seconds. I read yesterday that the MD3060 Allison does not have a neutral control switch.

If the voltages read OK (and I think they will) at the terminals, does anyone else have any suggestions. My only alternative is to wire a push button starter. I would just run a new wire to the solenoid, turn my ignition to run and then push an aftermarket button.
YC_1
Nomad
Sep 02, 2014
No reason to run a separate start button. Just find the wire that is supposed to start the thing, cut and splice a new wire where you are getting good voltage immediately and run it to the starter terminal. Of course this is not the heavy starter cable I am referring to. The solenoid that kicks in and sends the heavy current to the starter of course.

I seem to have an open wire on my RV as of a couple of days ago. Chasing it is all but impossible without my Fox and Hound tracing device.

Your description sure sounds like a lazy relay/poor contact.

If your signal passes through one of those relays shown in your picture try removing them one at a time to see if it PREvents the engine from turning over. If you find one that does, swap it with one of the others that has the same part number.