2002 Diplomat turn key nothing happens

[jdl2002dip]

It only happens sometimes and when it starts it can't be duplicated to trouble shoot. I turn the key and the coach does not start. Batteries are new. Could it be a relay. I notice my alert chimes for air bags don't chime when this happens. I fuss with the key and miraculous it will start. Any suggestions or someone else have same issue?

[arby]

Sounds like the ign switch went South. Most likely it is a GM switch and should be easy to find but you might need a special tool to get the bezel off.

[mahon1993]

Seconds on the ign switch. Did your whole ign switch rotate in the dash? That is, does the switch seem loose? When the switch is in the off position the key slot should be vertical. Mine spun around because it was loose and twisted some wires. I would check the plug on the back of the switch and make sure that it is snapped in tightly and that you don't have any loose wires on it. If it looks OK, I would head to a good auto parts store for a new switch.
Greg

[graduate78]

Check the wire splice off the main batteries, it could be loose or corrodied. It may be taped or have a shrink sleeve over it. I had the same problem on my02 windsor-why they put a butt splice there is beyond me. Hope this helps. Graduate78

[jdl2002dip]

Replaced the ignition switch. Before I had no noise. Now I have a tick sound that I can hear from the drivers side window. My dash all lights up. Radio works. Maybe a solenoid? Any help . Thank you

[clarkgriswold]

I had the same type problem with a 1999 National Class A. I took the ignition switch on multiple times only to see really no problem. Mine would start fine for a period of time. Then for no apparent reason I'd have nothing. Turns out is was the starter relay which was going south. The best I remember there was a starter solenoid and also a starter relay on my RV. I did a search and found the wiring schematic and isolated the problem....of course Camping World agreed and wanted to replace the wiring harness to the relay (at a huge cost). I didn't buy that and opted for them to simply change the relay which I could have done myself had I trusted my own diagnosis. Oh well.

First thing I would do is look for the schematic. Mine was on a Ford F53 frame so I had to find a Ford manual. If you find the schematic let me know and I'd be glad to help.

[Robi.1014]

JDL,
Important here is that a full ten (or so) "activation volts" is reaching the starter solenoid (the solenoid sits atop the engine's starter). Voltage-drops is our enemy here, and does occur throughout the RV system: at and within the ignition switch, and at each interconnect/plug connection along the path back to the solenoid's activation terminal. Loss of voltage translates into the condition where insufficient amperage is available for the the solenoid to "pick up".

If the starter-solenoid activation-voltage is marginal, this might explain why sometimes the motor will start, but other times you only hear it click. The main contacts within the solenoid (the contacts that carry the high current to the starter motor) REALLY need to be slammed together by a healthy solenoid action....else, the high-amperage connection can fail. You did state: "I fuss with the key and miraculous it will start."

How to troubleshoot:
Connect the red lead of a voltmeter to the solenoid at the solenoid activation terminal (which can be identified as the small-screw terminal next to the very large battery-cable connector on the solenoid). The black lead of the voltmeter must be connected to a known good chassis ground (can't get any better than the negative post of the starting battery).

Trouble is, of course: these two connections are several feet apart. Suggest that you make up a 10' single-conductor (16-gauge, or so) extension wire with alligator clips on each end. One alligator-clip connects (hopefully securely) to the solenoid's activation terminal. This needs to be a semi-permanent connection (for test purposes), so use black electrical tape or cable-ties to secure the wire as it proceeds away from the starter location and to an accessible location on the curb side of your coach (curb-side is where your batteries are located, right?). The other alligator clip connects to the red lead of the voltmeter. Don't let this connection accidentally touch ground!

So now you can run tests without being under the RV when your partner attempts to start the RV at the ignition switch. Observe the voltmeter's reading when the ignition switch is held in the start position. Let's assume in this case that the engine doesn't start: What is your reading? It should not be less than 9 volts. Watch this reading over 10 seconds or so (while the ignition switch is being held in the start position) ... does the voltage decrease over time?.....which implies a connection is heating up somewhere in the voltage-path.

Can this test-wire prove that the starter-solenoid itself is working or bad? Yup, kinda. With the ignition switch in the ON position, touch the free alligator-lead very briefly to the positive terminal of the starting battery. Does the starter attempt to work? If so: try a full start attempt (hold the alligator-lead there longer...and the engine will start). But if you only hear a click, then the starter solenoid (or perhaps the starter itself) needs to be replaced or overhauled.

What if you run the voltage-measurement test above, but the motor decides to start (darn it!!)? Well: you haven't learned anything yet. That's why I suggest securing the test lead in such a manner that you can use it in the future.

[clarkgriswold]

JDL.... keep in mind also that some have starter relays in addition to the solenoid and that can intermittent issues not associated with voltage. Just my 2 cents.

[jdl2002dip]

Thank you for everyone's input. The coach started and I am on my way. Still not sure what the problem was. Thanks again!

[Dan C]

Here's something entirely different to look at. I had the same problem, turn key and nothing. Turn key off, and usually the 2nd time it would start. The issue on my 07 Camelot was the control module for the Allison Tranny. That's the gear selector panel on your dash. When I would turn the key, and nothing would happen, the lights on the tranny panel were off. When I would turn the key a 2nd or 3rd time, the panel would light up, and the engine would start. If when you turn the key and nothing happens, check the lights on the tranny panel. If they're on, then this is not the issue. Just something else to check.

[JohnRR]

As already mentioned the ignition switch sounds like an excellent starting point, if it were mine I'd replace it just to be sure.

[86 Cavalcade]

I had a similar problem on my Diplomat as mentioned by Dan C. in a reply. In my battery compartment there is a single 7.5 amp fuse and the fuse was good but the fuse block was corroded and the engine would turn off and then back on like you were shutting the key off then back on. At times you had to turn the key on and off several times to get it to crank. This bad connection had gotten so hot that it melted the plastic on the fuse. I went to a boating store and bought a water proof fuse holder and have not had any problems since then. I went to an Allison service center and had them read the trans controller and they said I was having a loss of controller voltage and that is how this problem on mine was located. George 2001 Diplomat