Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Turn Signal Module - Lets build a better one!

Thanks Planenut

I'm not going anywhere now staying put in the UK, which is a relief !

Alister is a friend of mine and I'll pass on your notes, which will be appreciated. I'm going to help him build a better module.

All the best
Craig
BearDee

Thinking about this, surely the stalk is simply sending a one off ground for high beam and a separate one for flash selection to be converted to a CAN bus within the module - the electronics do not require a continuous ground as per a traditional mechanical latched relay hence the type of switch fitted. A separate ground and hence arm operation is required to either return high beam to main beam.

Modern electronic switches could be multiplexed where a ground or change of state is monitored.

My thoughts anyway but good that someone has this module apart.

Ok

Update from Alister...

Morgan Turn Signal Module E340098

4th May 2021

Scope.

This module has been causing trouble for a while. In particular, one failure mode causes the engine to continue to run even though the ignition key has been removed! My investigation has identified the reason for this and the next step is to redesign Electromech’s EA0021i4 circuit board to improve reliability.

Components.

There have been comments on the TalkMorgan site asking as to what is inside this unit. Here is a list of the main components:

1. Connector TE, 18-way
2. CPU: AVR megaAVR48
3. CMOS IC CD4072
4. 4 high-side current monitor ICs
5. 11 transistors
6. 3 diodes
7. 2 relays, OMRON G5LE-14.
8. 44 resistors
9. 5V regulator IC 78L05B.

The components have been carefully chosen: they are all rated AEC-Q100/Q101. But some components are obsolete. The case is marked internally RX3010 and has a rectangular slot approximately 16 x 45mm.

PCB.

The pcb is approximately 72 x 42mm and is smaller than the internal dimension of the case. It could be up to 72 x 47mm. It has filleted corners. Two of which are required to clear the case’s lid screw pillars. The other two are not required.

Current Sensing.

There are four high-side current sensor ICs ZXCT1109, and 4 series resistors. These monitor currents going to the indicators and repeaters as separate circuits. The repeater lamps are fed via 0.33 ohm resistors, one for left and one for right, and the main indicators are fed via 1 ohm resistors. This suggests that the repeater lamp is an incandescent bulb whereas the main indicators are LEDs.

The manufacturer’s data sheet application notes have been carefully followed.

CAN-Bus, Inputs and Outputs.

There is no CAN-Bus on this unit. The stalk switches momentarily ground a 5V feed from the TSM’s 5V regulator IC for the commands Left, Right and Dip/Main Beam. All three toggle the function, so to turn left the Left input is grounded for a fraction of a second. To cancel the latched Left command, either another Left grounded transition is required or a grounded Right. If the input is held low there is no change of state.

If the dashboard’s Hazards switch is pressed and held in then 12V is fed into the TSM. The microcontroller flashes all the indicators and repeaters at a different rate from a turn signal.

Left and Right lamps in the dashboard follow the indicators as they are on the same circuits.

I have not yet traced Pin 7, Loom wire LGK114. That’s it so far...

Very interesting info Craig it looks like he could be getting to the reasons why we get these odd failures.
Ian

Hey Ian - We will make a better one. We'll produce a few to start with and I'll fit one in my car to trial, keeping the original one onboard !
I'm also going to ask Alister to place the board on some silicone within a IP66 housing, which will keep the wether out! - Will keep everyone updated.

Well done BearDee for your efforts.
What controls the auto cancel timer, could this be made adjustable as I find it doesn't stay on long enough.

Agree with this, I also find it cancels before I pull up to a stop at a intersection. That CPU on the parts list is the brains behind the unit, and almost certainly controls the turn signal timing. It should be straightforward to change this timing when the replacement is programmed.

Hey Obie, I will ask the question to Alister. Good point.

+1

Another for a slightly longer indicator period, or a higher speed switch for it to keep it going. If you are rolling up to a junction it will cut out too early unless you are stopped. Great work 👍.