On my class C motor home, 1999 with V10 engine when I turn the ignition key to the start position I get absolute silence, when I release the key and turn it to the start position again it always starts. I have fitted a new starter motor, new solenoid and new battery but still the problem persists. I'm scared that one time it will not crank over on the second attempt.
Any one had this problem and know the fix ?
Thanks.

 

Your ignition switch is possibly out of adjustment or just plain going bad

 

Is the solenoid you replaced part of the new starter motor or do you also have a slave solenoid too?
It might be the problem if not already replaced.
With ignition switches, they usually work or don't. Seems odd to have it operate the second time consistently. You might have a bad wire connection too?
You might change your positive battery cable as they can wreak havoc too.
It happened on our boat a few years back. It looked perfect from the outside, corroded pretty bad once removed and inspected.

 

I've changed the slave solenoid. I'm suspicious of the switch but I will have a good look at the battery cables, I've also been thinking of fitting by-passing the key starter with a separately wired starter button.

 

Do a voltage drop test and see where in the system the failure is (youtube it). Also ohm out the secondary wires(battery cables). They can visually look good and be bad. Check and verify all grounds and positive connections are clean and tight this includes the primary (small control) and secondary wires. Is the chassis ground present and accounted for? How about the neutral safety switch? Try moving the shifter around with the key held in the start position the next time you start it and this problem occurs. Is the ignition switch Ford or the coach builders? Somethings moving with the first start attempt. Sounds like somethings lose or poorly grounded. Probe around with a VOM while someone turns and holds the key to see where the loss of voltage is.

 

The starter circuit on this vintage truck/chassis is what I call "stupid simple". It's nothing more that the ignition key switch, an inline fuse, the DTR switch (on automatic-equipped trucks), and the starter relay (which provides the higher current to operate the starter-installed Bendix solenoid. There's another high current cable that goes straight from the battery to the starter motor to run the actual electric motor when the Bendix solenoid is engaged.



Check the fuse first. F7 under the hood. Don't want to miss an easy fix.

Check for any significant voltage drop between the battery negative post and the engine block with the switch in the START position. This checks the ground cable.

If F7 is good, connect your meter lead or test lamp to one of F7's terminals (you can access the back of each " leg" via the little holes in the top of the fuse's plastic body. Turn the key and see if you have power. If no, then go test the ignition switch.

If yes, then connect the same test lead/light to the small terminal on the starter relay. Turn the key and see if you have power. If no, test the DTR switch (in both N and P positions).

If yes, observe whether or not the starter relay is "clicking" when the key is turned. If no, replace the relay.

If yes, verify the input (always hot) and output (START ONLY) voltages of the starter relay for nearly full battery voltage when in START. If the input drops way down, the battery is dead or there's a bad connection or cable between the relay and the battery. If the output drops, the relay is bad. If the output does not drop, check the feed at the starter and see if the voltage drops in that segment. There are a few more steps, but this will get you in the ballpark.

this isn't hard, you just need to patiently go through the process

 

Thank you both for the really good information. I've printed out your replies and this coming weekend I'll try to pin the problem down and fix it.

 

Let us know how it comes out, oldracer.

 

ProjectSHO89 has given you a good troubleshooting procedure.

While many things could cause your problem as stated above, your symptom actually sounds like a dirty/worn relay contact. Check for a starter relay in the power distribution box in the engine compartment. You might want to test or replace it as an easy first step, then, if necessary, go to the troubleshooting procedure listed above.

 

Good idea, except the 99 F53 Motorhome Chassis doesn't have a starter relay in an underhood fusebox. It's an external relay mounted on the RH radiator support near the AC accumulator unless the coach builder moved it after the chassis left the factory.

 

Here's the update, sorry it's been so long but I left Florida on the 15th. and am now up in Canada where it has been too cold to work on the driveway untill
today.
Thanks to the information posted, where I originaly stated that I had changed the slave solenoid, I had not! I had changed the on board generator solenoid which is right by the engine compartment battery by mistake, I did not know the slave solenoid was out of sight underneath the battery tray. Every thing checked out OK but I think that the old original solenoid was misfiring now and then and I have now replaced it. They don't make it easy to get at or easy to see. Any way, thanks to all you who gave me the advice and facts, I have now changed it and have the scars as proof. Time will tell if the problem has gone away but I feel confident about it.
Thanks again for all the information and advice.