Engine Does Not Crank--- Sometimes

[lewengel]

1998 Airstream MOHO on a XC chassis, Cat 3126.

Sometimes when I turn the key to start, nothing happens. Sometimes if I hold it in the start position for several seconds it will crank OK.

Today I noticed a “do not shift” light was on the dash but it did start. Is there a “neutral safety switch” or a relay in the circuit between the key and the starter solenoid? It is a push button shifter. I have a “Silverleaf” VMS that shows no faults. Does anyone have a schematic of this circuit.

The manual only shows a single line from the ignition switch to the starter solenoid.

[wolfe10]

There are a number of things that only work with the ignition ON-- Allison shift pad, dash HVAC fan, etc.

So, start by determining exactly what does/does not work that should only work with the ignition on.

The ignition switch is used as the signal for the IGNITION SOLENOID (different from start solenoid). If either the ignition switch or more likely the ignition solenoid is failing intermittently, it can cause your symptoms.

The other thing that will give puzzling symptoms is a loose or corroded terminal at battery and/or the ground lug.

Let us know what you find.

Brett

[lewengel]

The dash lights up when I turn the key on, low air red light and buzzer etc. The engine preheat goes on and times out. Sometimes it cranks right up, sometimes if I hold the key in the start position for several seconds it will evently start up. I cleaned all the battery terminals. Where is the ignition solenoid?

Lew

[wolfe10]

Lew, if the dash lights light up, the ignition solenoid is OK, as that is what powers them.

Suggest you get with Freightliner Gaffney for a wiring diagram. Intermittent problems are tough to diagnose, you need to troubleshoot when it is not working.

One other place to check is the ground wire on the engine. It is on the passenger's side, near the computer (black plastic cover). As with any electronic engine, it needs clean power to work. Just forward of there is the starter, Check that the connections are clean and tight.

Brett

[jdb7566]

I had a similar situation this past summer. Check the power terminals on the starter motor. On mine the large cables from the batteries were sulphated and cleaned up nicely with a baking powder solution, however, the small wire from the starter relay, was badly corroded. I replaced the starter and the bad terminal end and have had no problems since. I may not have had to replace the starter motor, however it appeared to be the original from 1999.

[lewengel]

I called Freightliner and they said that their is a box with relays in it, (at least one from the transmission) that the wire from the key goes through on its way to the starter. He said it is in the back somewere, shipped not mounted. Airstream must have mounted it somewhere. I will start looking under the bed (motor access).

[lewengel]

I called Freightliner and recieved the drawing. There are two relays in the circuit. Now to find them!!