Won't switch over - gloom and doom!

[JonC]

Hello folks, new here and delighted to find this abundance of experience.

I have a 98 Ford Explorer which has on it a “mongrel” single-point system as far as I can see. I’m loathe to say “installed” as I think the guy sort of threw a box of bits under the open bonnet as he ran away with the money (I didn’t have it fitted!).

It has:

Leonardo AEB 175 Controller
AEB 422 OBD2 µFix “C”
Lovato 783035 Emulator
Lovato AEB 366 “Addatore Sensore”

It also has what I’d call a “standard” switch i.e. red LED, yellow LED, rocker switch and a string of LEDs for fuel level.

It runs but it’s always had irritations. The level indication has never worked since I’ve had it so I just run on the trip clock (I don’t think it’s properly connected at the tank). It doesn’t switch back to petrol automatically if it runs out of LPG so that’s annoying (programming?). Sometimes none of the lights on the switch work at all for a while but you can always hear (and feel) if change to LPG. Sometimes it doesn’t change to LPG, then I get very sad but it usually doesn’t last more than half an hour, then suddenly the yellow light appears and everything’s nice again.

Looking at the Leo when I first noticed this stuff, I thought some of the soldering on the connectors was pretty dodgy (a few cracks appearing around pins) so I resoldered some but it didn’t improve anything. So I just put up with things and fixed a few of the other little nasties around the system. You know, little bugs like the tank falling off and so on!!!

Anyway, I let someone more patient and more adept with a soldering iron have a look at it a couple of days ago and he successfully resoldered all the connections on the small plug and one that looked a bit iffy on the big one.

Now I have no lights at all except an occasional and vaguely flashing red and it won’t switch to gas for anything!! It doesn’t respond to the switch, I can’t do the thing where you force it to start on LPG, it’s having none of it.

I had a probe around with a meter and the blue doesn’t go live. If I put 12V +ve on the blue pin, the solenoids open and a relay on the board also clicks. I think continuity between the switch and the Leo is ok because the voltages on the Leo connections changes when I operate the switch but I don’t know what they should be so I’ve no idea what’s right. There’s also near enough full alternator voltage on the two yellows while running and continuity between them when switched off (if that helps anything).

Any suggestions Gents? Before I run out of Prozac or cash!!!

Cheers,

Jon

[Gilbertd]

Not a mongrel but a fairly standard AEB175 Leonardo install. The Leo is the controller, the emulator is needed to fool the petrol ECU into thinking it is still running on petrol when it isn't (and a Lovato emulator is an AEB one with a different label), the AEB 422 is to stop the check engine lamp coming on all the time while the AEB 366 is a thing used to interface one sort of tank level sensor to a unit that requires a different sort (but, as the Leo can be programmed to accept just about every sensor type known to man, is probably not required).

From the top, a Ford Exploder on a single point system is an explosion waiting for a location if it is the V6 engine, the earlier straight 6 is OK though. General advice if you have the V6 is to not even try to run it on gas.

Warning over, now to the details. The Leo will not change over when it runs out of gas, you will just start to lose power so you flick the switch. It can be programmed to change back when the tank reaches a certain level but as the gauges are so notoriously inaccurate, you'll probably find it changing over if you go round a corner with less than half a tank so nobody ever programmes that feature.

Leos are usually pretty much bulletproof and well made too. I've repaired a few that have suffered due to abuse (no fuse instead of the recommended 7.5A fuse) and have never seen any dry solder joints. Assuming the Leo is now OK, look out for dodgy joints. There are a number of connections made to the cars electrics and if it has been installed as badly as you think, chances are that they are failing. You'll need to check everything and to help you, you can download the manual from here http://www.aeb.it/products/feedback-sys ... ttachment1 (English starts on page 20). Favourite places are corroded fuseholders and badly made earth connections. The yellow wires will do whatever you want them to do. They are simply connected to an internal relay that is made when on petrol and open circuit when on gas. Most installs don't use them.

[JonC]

Thanks for that! I've been reading your previous posts and already improved my understanding massively!

I should probably say I've had this truck two years and it's faults aren't new - they're just a long liust of things that I've been chipping away at. It's also my second Explorer - the first had a very nice Bigas multi-point system which worked beautifully. If it wasn't for the lights, you wouldn't have known it had switched!

This one though is a very different story. I'm also on the UK Explorer Forum and most of us are on gas. There aren't many straight sixes around and certainly all the Ford-sold (97 - 2000 were V6 motors. We've had all the Exploder gags but we like out motors. I;ve had the explosion too - blew the back end completely out of the upper manifold and I felt it hit the bulkhead!

One of the more learned members of the Explorer Forum did a very good write-up on why and how and apparently it's do do with the speed (or lack of it) at which the processor updates.

Anyway, back to mine. As I said, the switch always worked and the lights usually did (except the gauge) but occasionally the lights would go out while the system still functioned normally behind that. So,. my first stop was at the Leo connections because it is literally thrown into the engine bay (loose) and when disturbed, things seemed to change. A close look at where the pins entered the board revealed the kind of joint cracking we used to see in the older days of Philips kit when I was doing TV and electronics.

That said, my initial efforts at re-soldering didn't achieve a massive improvement so maybe it was never that in the first place. The thing is - without fully understanding the interactions of the various modules - I didn't have much idea of what did what.

I'll post some photos when I get some daylight but it really is badly fitted. There's lots of little clues; the jubilee clip that holds the mixer has torn the under-bonnet liner, the first solenoid is under the left front wing - right in front of the wheel and the evaporator is fitted in the engine bay just high enough to knock a relay box of its location and not allow it to go back!

I won't even try to describe the wiring mods - think Stanley blade and black tape and you've got it!

Do you happen to know what I should expect at the switch I/O? I'm trying to work out why there's neither the gas nor petrol light coming on and just how the whole switch/gauge works down just four wires!

[rossko]

I believe the switch wires carry +12v or is it +5V, gnd, switch, and proprietary serial (to control the lights)
Have a look at where the cable is routed through bulkhead etc. for chafing

[JonC]

Ta muchly!!

I suspect +5V as I measured something like 4.6ish when I was poking around.

Would it be sensible to assume that the switch returns that voltage on the other half of that pair then? I've got red & black and brown & blue.

If I can figure out the functions of the pairs, maybe I can rig a few simulations to see which end isn't working and also perhaps test the switch without cremating anything!!

[Gilbertd]

No, it's a data connection between the controller and the switch, nothing as simple as on/off or analogue signals. I've got a spare Leo unit complete with loom and switch, I may have time tomorrow to power it up and measure what is on each wire.

[rossko]

I suspect the switch is a simple level, input to the ECU. While the serial is one-way only to the lights controller.

[JonC]

It would be great to have a better understanding of all this, there's so much I want to do (or undo!!) on it!!

There's a nice 90 litre tank in my gsrage waiting to meet the underside of my truck but when I do that, I want to clear up a whole list of nasties at the same time.

Meanwhile I'm hoping for decent weather tomorrow in which case I'll take the afternoon off and explore (sic) the wiring. At 50 miles a day, I can't afford many days on petrol!!!

[JonC]

Evening gents!

Thanks to everyone for the advice so far. I haven't improved anything except my understanding but my confidence in both myself and the Leo system has also increased.

I did wonder earlier if perhaps we'd inadvertantly (ok then, clumsily) introduced a short on the board so that the Leo thought it was switched to petrol all the time so tonight I had another poke around. I took some readings in the hope that they'll mean something to the more learned members so here's what we have:

On gas: Red - 2.35v, Black - 0V. Brown 4.04V, Blue 2.36V
On petrol: Red 2.45V, Black 0v. Brown, 4,09V, Blue 0V

Doesn't mean a lot to me other than to say the Leo is seeing the switch. I also know that the stepper motor powers up when you re-connect the Leo (if that's any significance).

Any clues?

Cheers

[Gilbertd]

I was just about to hang my spare Leo onto a 12v bench supply and check the voltages on that but realised that my spare stepper is in the boot of the car and it's bloody freezing out there! So, without being able to try a complete system, it may not prove a lot. However, from the readings you got, I would say you have a high resistance connection on either the permanent or ignition switched supply. The Leo contains a 5v regulator so I would expect to see either 12 or 5 volts on at least one of the pins. Even if the battery voltage was down a bit, then the 5v rail would still be at 5v and not 4v.

Where in the country are you? If you aren't too far from me it wouldn't take long to swap your Leo with my known working spare to prove if it is the Leo or the wiring.

[JonC]

Gilbert you inspire me!!

Yes, the brass monkeys are looking a bit concerned here too but I have bigger fish to fry so damn the cold!!

Right, all measurements wrt battery negative - we have a static battery voltage (ignition off) of 12.42.

Ignition on, we have 12.06.

On the Leo, SW+ reads 11.90 and fused + reads 11.96.

I'm just outside Derby so it's a bit of a trek (££££) but it's a very kind offer and one I may very well take up, especially if it means drving back on gas!

Over to you Sir!

[Gilbertd]

You're definitely losing some voltage there and it may be that when it tries to switch over and pull in the solenoids, the additional current being drawn will cause the voltage to drop considerably. I'd say to have a very close look at the switched supply and the system earths.

[JonC]

Well there's a couple of things I can quickly do in that case - I can run a wire straight from the battery just as a quick test and I canput a meter on the blue output because I don't think it even tries to switch.

In that vein, could it perhaps not be getting the rpm input on the brown? I don't suppose that's something I can measure plus having individual "coil" packs, would it be taken from the rev counter?

They're for tomorrow anyway...........

[Gilbertd]

Brown could come of the trigger wire to any of the coils, the Leo only needs to see pulses, equally it could be taken from the rev counter feed. Just depends how the original installer decided to do it. To switch it's going to need both supplies and an rpm pulse that exceeds whatever revs it's been programmed to switch at.

I'm still a bit concerned that you've got no lights on the switch, you should have one or the other and yes, the stepper will move when the system is first powered up so something is doing something.

[JonC]

Well yes, that's the thing that gets me.

It switched at 2000 but to go back to the beginning, the lights were always sporadic yet the system would usually operate correctly regardless - it just didn't announce it and then the yellow light would usually come back later.

All I have now is a very brief, faint and very occasional flash of the red. I was also a bit surprised to hear relay activity when I jumped 12V onto the blue output.

I thought that would only feed backwards as far as the open relay contact.

[Gilbertd]

What you probably heard was the relay on the yellow wires. I suspect (and if I could be bothered could probably trace the circuit) that this normally closed relay is operated from the blue wire output of the main switching relay. By putting 12v on the blue wire that would cause it to operate.

[rossko]

The yellow-wire-relay is multifunctional, and can do different things under software control, it'll have a seperate driver.

Rule of thumb; any mystery electrical gremlins = bad earth.
Although I'd be suspicious of the indication of a wonky +5V supply here.

[JonC]

Right folks, this may be my last post if I don't get somewhere - after two weeks on petrol, I'll be shopping for a Leonard Cohen album and a packet of razor blades!!

It's a nice day today - the first in a while - so having that special combination of dry, warm, daylight and time, I;ve been quite righteous and given the old girl a good dose of looking-at.

Found lots of potentially @!## earths and they're not all from the gas "installer" - even the original Ford body earth was on paint ffs!!! Having said that, every piece of the gas kit has its own, separate earth, attached to something found strewn around the engine bay. Why he couldn't just get a Durite terminal block or similar, who knows!!

So, starting from a position of 4 ohms (and bear in mind this has been working for the two years I've had it, I've got it down to <1.

Sorted the body earth, fixed a few @!## connections along the way and consolidated some of the gas system earths. How much has it improved things? SFA!!!

Got the same voltage across supply and ground on the Leo that I've got across the battery but still only reading just over 4V on the switch output.

That's it now - I really am out of ideas!!

[rossko]

It used to work.
Someone messed with remaking connections, its never worked since.
What do you reckon?
I think it'll have to be fingertip through the wiring to see whats happened, not so much for condition as swapsies or omissions.

[Gilbertd]

Measuring resistance to earth is an indication but not ideal. Think about it, if you are measuring the resistance between an earth point and battery negative and getting 1 Ohm, you might think that is good but it isn't. Because that 1 Ohm has quite an effect when you try to draw current through it and the voltage will drop.

From how I read your post, you've got 12v going into the Leo but only 4v coming out on the blue wire. Measure the voltage on the input when you are seeing 4v on the output and I suspect you will be seeing 4v there too. What is happening is that there is a high resistance somewhere (in a fuseholder, or at the main earth) so with no current being drawn, you will see 12v. As soon as you try to make it draw any appreciable amount of current, the resistance comes into play and the voltage drops. The way to check to see how much it drops is to measure the volts between the live o the battery and whatever it is you are testing. If the meter reads zero, all is fine, but if you are dropping voltage through a bad connection somewhere you will read something. In your case, I would expect you to read 8v, the difference between what goes in and what comes out.

Takes all the earths to a common point and run a wire from there back to the negative of the battery. Don't use crimp connectors, especially not those horrible colour coded plastic things, twist the wires together and solder them (all joints should be soldered to meet CoP11 anyway). Then get yourself a spare headlight bulb as it will draw roughly the same amount of current as the Leo and a couple of solenoids. Connect one side to battery negative and the other side to wherever you want to test. Using the bulb as a load, then check the voltage. So if you connect the bulb to the input of the Leo and measure what you have at that point. I suspect the bulb will only light dimly and you'll see less than 12v. Don't forget that the Leo has two supplies, permanent live and ignition switched (red and red/black). Make sure you check both.