Failure to crank

by Bob Collins in 912iS Technical Questions 4 weeks ago

Hi:

I'm going through the Van's Aircraft Production Acceptance Procedures for my RV-12iS. I ran into a problem today. The starter circuit won't engage.

This particular step in the PAP calls for a test of the wing pin sensors. When the wing pin is not secured, it should override the ignition module.

The red button on the ignition module is on and the wing pin is removed from its secure position. Turn the key. Nothing. Good. Put the wing pin back in its secure spot, the red light goes out, turn the key. Nothing.

Multiple attempts over several days revealed the same results. I also tried with the EMS battery on. Nothing.

I went over the wiring and everything is as it should be. I checked continuity to be sure there was no wire break and, again, everything is fine.

I removed the second G3X unit to be sure the HIC module is secure and to get a look at the LED light. It glows the bright white. I did have a couple of times when I tried today where it was green. Why it was green, and later went back to white, I don't know. (See picture)

Checked all fuses in the panel and in the ROTAX fuse box and all are OK.

As you can see in the attached picture, the LANE A fault light is on. But that's because the bottom cowl is off and disconnected from the air filter, etc. One thing you'll note above is the red "X" on the oil pressure. Although I haven't done a lot of looking at the G3X with Lane B on, this is the first time I recall seeing that "X". I checked the connection with the oil pressure sensor and it is fine. (See picture)

Are these two separate issues? Or are they somehow related? Who knows.

I did upgrade the HIC, following Van's SB-00058. However, the reported problems that spawned that service bulletin were related to the fuel pump (which might explain the fuel pumps cutting out after about 15 seconds when I tested them the other day. I hadn't experienced that before and just did a lengthy fuel flow test last week) rather than the failure to crank at all. I have not yet done a firmware update on the ignition module (as required by Van's Service Letter SL-00072) although I ordered the part several weeks ago. I believe it's stuck in Van's new "grouping orders" process.

My question here: does any of this sound like something the firmware upgrade would solve (yes, it's pre-2023)? Or do I just have a bad ignition module. I'm not real keen on spending $423 to find out, and start buying and installing parts not knowing where exactly the problem lies.

Any advice you can provide would be very much appreciated.

10969_1_PXL_20250601_182546621.jpg (You do not have access to download this file.)

10969_1_PXL_20250601_182536448.jpg (You do not have access to download this file.)

10969_1_PXL_20250601_174543608.jpg (You do not have access to download this file.)

Re: Failure to crank

by Bob Collins » 3 weeks ago

Bob Collins

3 4 10

Any advice at all.

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Re: Failure to crank

by Jeff B » 3 weeks ago

Jeff B

14 718 2.61k

Bob,

I think the lack of responses is do to many of us being unfamiliar with the specific electrical components used in the Vans RV12iS. This is likely an aircraft wiring problem rather than a problem with the Rotax system. Since the Rotax 912iS does not use ignition modules, I assume you are talking about the Vans ignition control module which controls the timing of the application of start power. Also, I believe the Vans HIC modules are simply a wiring interface between the HIC connectors and the aircraft wiring. That said…

I don’t think this is a problem with the Vans ignition control module. This module can interrupt the start power circuit, which would also interrupt power to the starter relay. But that would also shut down the fuel pumps and ECU lanes, which does not appear to be happening.

The starter relay control power originates at fuse 18 in the Rotax fuse box. It then leaves the fusebox as a red wire via pin 5 of the X1 connector. From there is goes through the wiring harness to pin 12 of the HIC-B connector. This does not go through the ECU, it’s a simple fused power circuit so would not be affected by a lane fault. From the HIC connector the power would likely route via the aircraft wiring to the start switch and through any Vans specific safety devices like the wing pin switches, and then back to pin 4 of the HIC-B connector, where it becomes a white wire in the harness and routes to the starter relay. The white wire at the starter relay coil is the 12V+. The black wire at the starter relay coil is the ground (12V -).

The first thing to do is see if power is getting to the starter relay coil when you are attempting to crank the engine. I would disconnect the power wire from the starter relay to the starter for safety, then engage the starter switch and see if there is 12 volts across the black and white wires at the starter relay coil. If not, you need to trace the circuit back and see where the start relay control power is interrupted.

Thank you said by: RotaxOwner Admin

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Re: Failure to crank

by Bob Collins » 3 weeks ago

Bob Collins

3 4 10

Thank you, Jeff. This is going to be a much bigger problem than I'd imagined

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Failure to crank

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