Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 Revs not going to idle

This winter, I did on both our M3W's necessary Centa upgrades.
For one of the cars with the idling problems, I did a thorough visual check on the engine cable loom and the chassis cable loom.
I couldn't find any discrepancies.

Last week was finely good weather to do a first test ride. Centa worked fine now, and all the rattling noise inside the Centa was gone. But the intermitted fast idling was still there.
Most of the time, it runs well in idle, but without any reason, it remains at 2500 rpm when coasting and drops to normal at a standstill. The engine light remains off during this. Sometimes at a standstill, the engine light comes briefly on, and the idle goes up to 2500.
So still the same annoying problem (see my explanation in previous posts on Talk Morgan; Revs not going to idle).
During this test ride, we discovered that the main lights didn't work; only the parking lights turned on. The green light indicator in the speedo was illuminated.

I started a new search.
I found out that fuses 7,9, and 10 were blown. So I replaced those.
All lights worked normally again. With the exemption that the high beam only works when pulling the stalk switch at the steering wheel towards you (signal mode) and does not work when pushing away from you.

And now the problem even got worse and a second problem arose.
When the contact key is OFF and I turn on the switch from the alarm lights the fuel pump starts running and the oil pressure light comes on!
But the alarm lights don't work.

When I switch ON the contact key without starting the engine, the fuel pump comes on like normal, and when I switch on the alarm lights, they blink normally.

I disconnected the chassis loom from the engine loom. I turned the contact key on and off, and on both occasions, the alarm lights worked normally, with and without the contact key turned. Now the alarm switch didn't start the fuel pump running.
I connected both looms again and disconnected the ECU. The alarm lights worked normally again, with and without the contact key turned. The fuel pump didn't start running when I switched on the alarm lights.

I swapped the TSM module (C16 turn signal module and head light unit) with the one from our other car and it even got crazier.
With that TSM module from the other car, switching on the main lights directly trip the 20 Amp fuse number 7 fuse number 9 and fuse number 10.
But that tripping of the fuses doesn't happen with the original TSM. It happens ONLY with the TSM from the other car.
With this other TSM installed and leaving fuse 9 out, the fuel pump doesn't start running when I turn on the alarm switch but turns on the oil pressure light. This is with the contact key in OFF.

When I disconnect the TSM unit from the system and turn on the alarm switch, the fuel pump starts, and the oil pressure light comes on. This is with the contact key in OFF.

I swapped the ECU with the other car, but all this mystery behaviour remained the same.
So it probably doesn't have anything to do with the ECU.
I tried swapping the ECUs last autumn as well when searching for the high idling, without any results.

I disconnected the two connections at the speedometer, as Planenut gave me that suggestion last year, but that also didn't change anything.

I've already swapped all diode relays, but that doesn't make any difference.

What this all has to do with the intermitted high idling, I don’t know, but for sure, there is something wrong. But what?

Can you imagine I’m getting desperate? Who can help me?

Laurens, this sounds very confusing.

The only data point I can give you is that my three wheeler sometimes idles fast when coasting to a stop too, with the same symptom that it drops to normal as soon as the wheels stop turning. But it only does this occasionally. However I have none of your other symptoms, so maybe you have two separate issues?

Laurens, some of those issues seem to point at the TSM module, you have tried the module from the good car, but have you tried the TSM module from the bad car in the good car and check that it all works ok.

Hi Lauren's, there is a lot to understand there. Reading between the lines, and pure speculation but could your idle issue be a mechanical or component issue, air leak or IAC valve for example since all your component swaps including ECU have changed nothing.

Secondly regarding electrical issues can I assume by "contact switch" you mean ignition switch? Also could you explain what you mean by"alarm", hazard warning lights maybe since you refer in same context to flashing? I can then look to see what is in common with the three fuses (7, 9, 10) that blow. Given that you found these fuses already blown before you swapped TSM, first thoughts are a wiring loom issue though.

@JohnMat. Thanks. Good to know I’m not alone with with this annoying problem. BTW if you disconnect the speed sensor at the right wheel is the high idling also permanent gone ?

@RogG. I’ve tried in the good car both TSM working normal. Equal which TSM is in.
If I put In the bad car the TSM from the good car it blows the fuses 7 -9 -10 when I turn on the main lights.
If I put the TSM from the bad car in the bad car the fuses don’t blow when turning on the main lights.
If I switch on the alarm lights in the bad car without switching on the ignition (key) the fuel pump start running equal which TSM is in.

@Richard. I’ve swapped all engine components one by one as far as possible. Including the whole throttle housing with all components from the good car to the bad car. No results.
With contact switch I mean turning the key at the steering wheel in on position.
With alarm lights I mean when both turn signals starts blinking together. Perhaps hazard warning light is more correct.
About the fuses see above to RogG

@All. Just back from a new test ride. 15 km. normal idling when coasting. Next 5 km. intermittently high idling. Disconnect speed sensor at front wheel from that moment on normal idling all the time without speed indication. Connect speed sensor again, next 10km. normal idling. Suddenly out of the blue high idling again. You can feel this high idling is back as the reaction from the engine specially when going downhill.
Now all lights working normal again. 😳
Switch hazard lights still turns on the fuel pump. 😱

Laurens, what a nightmare.

A few week ago while driving at north on an unlit motorway I lost all instrument lights, indicators, side lights and cooling fan. Thankfully headlights and engine kept running until I got home. When I turned the engine off it would not then turn over. Further investigation found 3 blown 5 amp fuses the indicator flasher relay and the cooling fan relay. Never found out what caused the failures.

5 years ago with the ignition off and key not even in, if I turned the hazard warning lights on the fuel pump would energise and I could start the engine. This thankfully has sorted itself out.

I think you have multiple small faults which will be very hard to figure out, could even be as simple as corrossion in one or two multi plugs giving intermittent multiple faults.

Best of luck with your investigations.

Thanks for confirmation Laurens. Will just comment on the fuel pump issue for the moment. Normally this is fed by the engine relay feeding to fuse 12 then via the inertia switch to fuel pump. The coil for this relay is fed directly from ignition switch with a ground signal directly from ECU to trigger relay and so energise pump. When this happens power is also supplied from relay to fuse 5 (ECU) and fuse 6 (immobiliser). The only possibility I can see for pump to run with ignition switch off is for a permanently live back feed through one or other fuse. I think we can discount the ECU which leaves immobiliser. When you have pump running with hazard switch on but ignition off, try removing fuse 6 ahd see if it stops.

How the hazard switch itself back feeds is still a mystery but one step at a time. One point I did notice on the pre-2014 wiring diagram, which I believe covers both your cars, is that diodes have been inserted in the left and right indicator circuit's between bomb tails and panel switch. Guessing this is to maintain isolation of each indicator side when hazards are off. The two diodes inserted in green/white and green/red cables should be seen close to panel connector concerned with switches, but did wonder if their shrink wrap covering has worn through allowing a short!

Hi Laurens,

Electrical issues are always a nightmare and it may well be you have more than one fault. If anyone can decipher the wiring diagram then it's Richard V6.

A couple of thoughts from me:

With the fuses blowing something is shorting or feeding in reverse most likely due to a bad earth or connector.

You mentioned the headlamp main beam doesn't come on when you push the indicator stalk so swap out the main beam relay.

Carefully check the connectors for the TSM and engine to chassis loom. It's possible one or more pins in the plug or socket have bent or been pushed into the housing or corroded.

Check all the earthing points for the chassis and engine loom. Hopefully Richard will be able to tell you from the wiring diagram how ma y there are and possible locations.

Good luck

Chris

Check the electrical wires behind the dashboard, despite no problem for me, the electrical wires were worn by rubbing on the instrument clusters with the engine vibrations.

I'm still investigating but that area is a good starting point to look for a short that would cause fuses 7, 9, 10 to blow simultaneously. Obviously check wires to light switch and back to connector, particularly the solid blue wire which becomes live when headlamp selected. This same blue wire feeds via main loom to provide switched power to main/dip headlamp relay and and then loops back at relay with same colour wire to TSM so worth tracing both runs for shorts.