Engine keeps turning over with key off?

[Krash]

Well, I have just had my starter replaced by a mobile mechanic. Not happy about the $600 cost, but I was at the pumps at a truck stop blocking its use.

Prior to the coach not starting, I was getting a weird situation where the starter kept cranking even with the key off? It would do this until I turned the key back on, and then the engine would start. So it appears that something is keeping power to the starter even with the key off. I thought the new starter would solve the problem, but no such luck.

After driving a few hundred miles, it is now doing it again? Key on, wait to start light off, crank for 10 seconds or so, key back to off, still cranking, key back to on, starts right up? No solenoid that I can find, and the starter is wired in directly from batteries. I know the solenoid is part of the starter, so that is now new also. Are there any other relays that I can check that signal the starter to engage?

Any other ideas?

[twinboat]

There is probably a relay ( solenoid ) in the starters solenoid feed. They call it a slave solenoid.

The start signal from the key actavates that, and that sends battery power to the starter mounted solenoid.

See if you can follow the S wire ( 10 or 12 gauge ) from your starter mounted solenoid towards the batteries. The slave solenoid will be in that circuit.

[miniceptor86]

My F150 and the E450 gas I drive at "work" if I may call it that continue cranking until they start just by cycling the key to the start position and letting it return to the on position. I don't know what senses that the engine has started. But then why are you turning the key to off? Turning the key off probably shuts the fuel off but the control module still wants crank. What I'd do is turn it to start, let the key return to run and be happy. Once it starts then for what ever reason you have the need to turn the key to off, it should stop running with out the starter cranking.

[Krash]

Thanks twinboat, I will look for that in the morning and report back.

miniceptor, the reason I turn the key off is that after 10 seconds of cranking, if the engine hasn’t started, I know something is not right. If I cranked it for more than that, I run the risk of overheating the battery cables.

I have never owned a vehicle that does what you describe, just keep cranking until the engine starts, but I guess newer models do that. I just wonder what such a system would do after 2 minutes of cranking the engine over with a no-start condition?

[noice74]

It sounds like you have a faulty ignition switch. It gets its input from the position of the ignition key cylinder and with out knowing what Engine or chassis manufacturer is. The location of the switch is undetermined

[billdreamlv]

Originally Posted by noice74

It sounds like you have a faulty ignition switch. It gets its input from the position of the ignition key cylinder and with out knowing what Engine or chassis manufacturer is. The location of the switch is undetermined

I could be the ignition switch but more likely the slave relay or solenoid. The slave is there to allow you to have a lesser gauge wire from the ignition switch to the starter solenoid. Then the starter solenoid is tripped by the slave solenoid. It is a way to use a smaller wire all the way back to the rear of the coach and still trip the starter solenoid.

The ignition switch usually, when faulty, will cause no voltage to the relay or slave relay rather than voltage all the time. I think the slave is stuck but when you drive it it loosens up and disengages at some point during the trip. This will definitely burn up your starter after a while if left on. Twinboat has a little more time under the hood than I do, and I think he nailed it. Listen for a click while you have someone turn the key on and you might find the slave relay. If it sticks, you will only get one chance to hear it. Good luck.

[miniceptor86]

Originally Posted by Krash

Thanks twinboat, I will look for that in the morning and report back.

miniceptor, the reason I turn the key off is that after 10 seconds of cranking, if the engine hasn’t started, I know something is not right. If I cranked it for more than that, I run the risk of overheating the battery cables.

I have never owned a vehicle that does what you describe, just keep cranking until the engine starts, but I guess newer models do that. I just wonder what such a system would do after 2 minutes of cranking the engine over with a no-start condition?

I don't know what happens if the don't start, they always do but I would imagine that someone thought of that when designing the system. I'll check the OM on my pickup.

[miniceptor86]

OM says it will continue to crank for 15 seconds.

[twinboat]

Originally Posted by miniceptor86

OM says it will continue to crank for 15 seconds.

Your not going to find that feature on a older diesel MH engine.

[miniceptor86]

Originally Posted by twinboat

Your not going to find that feature on a older diesel MH engine.

Didn't know, just an idea.

[MRUSA14]

If it cranks without you holding the starter switch it is not a feature, it is a fault. The starter solenoid, starter switch, or associated wiring is defective. This is likely what killed the starter.

[rick kirby]

Originally Posted by Krash

Well, I have just had my starter replaced by a mobile mechanic. Not happy about the $600 cost, but I was at the pumps at a truck stop blocking its use.

Prior to the coach not starting, I was getting a weird situation where the starter kept cranking even with the key off? It would do this until I turned the key back on, and then the engine would start. So it appears that something is keeping power to the starter even with the key off. I thought the new starter would solve the problem, but no such luck.

After driving a few hundred miles, it is now doing it again? Key on, wait to start light off, crank for 10 seconds or so, key back to off, still cranking, key back to on, starts right up? No solenoid that I can find, and the starter is wired in directly from batteries. I know the solenoid is part of the starter, so that is now new also. Are there any other relays that I can check that signal the starter to engage?

Any other ideas?

have someone check into the crankshaft sensor, my jeep did the exact same thing after it just stopped going down the road, they replaced the ignition module and the crankshaft senor and all is good. they informed me that new vehicles are like this if the motor doesn't fire right up...screwy.

[Toribk]

Krash,

This is a photo of a popular "slave relay" so you have an idea of what your looking for.

Typically, it is mounted somewhere in close proximity to the starter depending on the chassis manufacturer.

[TQ60]

You should locate the wiring diagram of the starting circuit and check things out with a voltmeter to see what is really happening.

So far the first "guess" was $600.00...

Many trained folks guess with customers money...

Sounds like a "start control signal" is staying in "start" mode so first action is to determine where it comes from and check there then along the way.

If intermittent then more difficult but clip leads are your friend as a test light or volt meter can be left attached to indicate the voltage when working properly and not.

Could be as simple as a loose wire at key switch almost touching another that touches when key pressure or a sticking relay which is caused by the contacts pitting and sticking.

That is common when too small of relay is used and they arc every time a make or break condition happens.