Lesharo automatic controller

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Lesharo automatic controller

Unread postby kramit » Wed Aug 08, 2018 10:05 pm

I have had an intermittent transmission computer for several years now. For the most part, it worked more than it didn't. But when it isn't working and stays in limp mode, it is quite annoying. Anyhow, it has become even more problematic. I finally narrowed the problem down to the transmission computer. I opened the computer and was greeted with a massive blob of some sort of rubber potting compound. I was able to push on the potting compound and recreate the intermittent problem. Perfect, all I have to do is remove the potting compound. Now that's where the problems start. I don't know if anybody else is crazy enough to pick away at all of that rubber but let me say that this unit was not designed to be serviced. That being said, I have given up on getting the circuit out.


I am looking at three options at this point.


How common are these computers on the used market? Do any of our members have spares to sell?


Since I program microcontrollers, another option is to build a circuit that will monitor engine speed and decide when to actuate the EL1 and EL2 solenoids. I am not sure how much time I want to dedicate to designing a controller for this old transmission.


Finally, I can do the modification to switch the transmission manually. I am a little concerned that one could accidentally shift from 3rd to 1st causing some major engine damage if driving at speed. (Hence the suggestion to come to a stop while in 3rd gear). Ideally, I would lprefer the automatic transmission to actually be automated.


Any comments


Mark,
1986 LeSharo gas, automatic
Montreal





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Re: Lesharo automatic controller

Unread postby scott.edwards » Wed Aug 08, 2018 10:19 pm

Hi Mark,


I just sold a used controller..... too bad. They are available..... as people change to GM or whatever, the old ones become available.... Perhaps someone will chime in.


Your options, on a practical sense are probably a new used controller, or the john switch. My preference is to keep it stock..... with the John switch as a back up. The thought of building a controller is interesting, but unless you are retired and have nothing better to do...wow, the time to make that right.....


If you are still looking when I do my conversion to diesel, I'll save the controller for you..... but don't hold your breath....


Good luck with the fix..... It'll be worth it in the end.


Cheers, Scott

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Re: Lesharo automatic controller

Unread postby kramit » Wed Aug 15, 2018 6:00 pm

Hi Guys, here is my update. I picked up a transmission controller at Robert Marleau garage. The transmission shifts fine now but here is the stumper. The engine doesn't run properly unless I push the fuel enrichening circuit. (I had to bypass the original auto cold start circuit). I feels as if the vehicle is starving for fuel. I can keep it running but only with the cold start circuit engaged. If I start the vehicle with the new controller and swap back in my defective controller, without the multipurpose switch, speed sensor or EL1, EL2 connector, the engine runs fine but is, of course, in limp mode, as expected. Even with the 6 pin connector removed completely, the engine runs fine. As soon as I plug the connector into the new controller, the engine needs enrichening in order to run under power. How can the transmission controller possibly have an effect on engine performance!!?? Any ideas? Thanks,


Mark








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Re: Lesharo automatic controller

Unread postby kramit » Wed Aug 15, 2018 6:18 pm

UPDATE. I picked up a controller from Robert Marleau garage. The transmission shifts fine now but the engine doesn't! The engine idles but will not drive unless I keep the fuel enrichening circuit engaged. (I had to bypass the cold start circuit with a push button). If I disconnect the 6 pin plug from the "new" controller,the engine runs fine. If I connect the 6 pin plug to the defective controller, it also runs fine. (Of course, it won't shift properly). If I connect to the "new" controller, the engine sounds as if it is fuel starved. These 6 pins are +12 volts and ground for the computer, 12 volt feed to the backup lights, starter enable out, kickdown switch and backup lights. How could any of these possibly affect engine performance!!?? I am stumped. Any ideas? Thanks,

Mark,
1986 LeSharo gas, automatic
Montreal











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Re: Lesharo automatic controller

Unread postby kramit » Wed Aug 15, 2018 6:59 pm

UPDATE. I picked up a controller from Robert Marleau garage. The transmission works fine now but the engine doesn't ! The engine idles but will not drive unless I keep the fuel enrichening circuit engaged. (I had to bypass the cold start circuit with a push button). If I disconnect the 6 pin plug from the "new" controller,the engine runs fine. If I connect the 6 pin plug to the defective controller, it also runs fine. (Of course, it won't shift properly). If I connect to the "new" controller, the engine sounds as if it is fuel starved. These six pins are +12 volts and ground for the computer, 12 volt feed to the backup lights, starter enable out, kickdown switch and backup lights. How could any of these possibly affect engine performance!!?? I am stumped. Any ideas? Thanks,


Mark,


1986 LeSharo gas, automatic


Montreal

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Re: Lesharo automatic controller

Unread postby kramit » Wed Aug 15, 2018 10:04 pm

(Sorry about the previous doubled messages. Trouble with one of my computers.)

I have checked which specific wire from the 6 pin connector on the transmission controller affects engine performance. It is the starter wire from the transmission computer. I thought this wire only goes to the starter solenoid so why it should affect anything else is beyond me. I shut off the motor and turned the key to the run position. As I move the transmission lever from P to drive, I hear some weird noises in the engine bay. I would think that there might be some crossed wires that are affected when the transmission is not in a position that it can be started. But my other query is why did it start and run perfectly fine with the old transmission controller? If something is wrong with the start control wire then it should have appeared with the old malfunctioning controller.
I will keep digging. Any ideas are welcome.


Mark

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Re: Lesharo automatic controller

Unread postby kramit » Wed Aug 15, 2018 11:59 pm

OK guys, I have more information. On my old controller, somebody added a jumper from the multipurpose switch red wire(starter motor authorization) to the third wire from the transmission controller (starter). Perhaps the controller starter output on the old controller was not functional. I imagine that I could add the jumper back and remove the pin from the connector so I don't have output from both the multipurpose switch (ground) and I imagine 12 volts from the transmission controller but I prefer to restore the wiring back to stock. As far as I can tell, the controller output a ground when in the start position and logic HI (I was getting around 5 volts but expected to see 12 volts!?). Does anybody have experience with this?

Also, although it is difficult to find, when the key is in the run position, there is a small noise in the engine compartment. The moment that I put the transmission into any of the drive positions, it sounds like the fuel pump runs continuously. Also, it make a sound as if the injectors are spraying fuel into the manifold. I don't think this is happening because the manifold would have filled up by now. I can make the noise stop by pushing my cold start enrichening switch.


My theory is that for some reason, the old controller stopped outputting a ground or voltage to energize the starting relay circuit. Somebody bypassed this by using the signal from the multipurpose switch. That being said, they might have done other modifications to make the bypass work.


I need to figure out why drive positions seem to energize various relays that are not supposed to be energized.
What voltage levels is the controller outputting to the starter circuit?


Sigh...........




Mark


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Re: Lesharo automatic controller

Unread postby scott.edwards » Sun Aug 19, 2018 1:50 pm

Hi Mark,


I don't have a wiring schematic in front of me, but is it possible that the fuse board connections are starting to fail, or the main power relays are failing? If current is limited by either of these power feeds, could it be that powering the transmission is affecting power to the engine, or fuel pump circuit?


Is there perhaps a short on one of the outputs, like the reverse lights????? even though it is not in reverse usually, probably in park.


Just some suggestions.


Cheers, Scott
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Re: Lesharo automatic controller

Unread postby kramit » Sun Aug 19, 2018 3:40 pm

Hi Scott, thanks for the reply. I have done more tests and I think that rules out your suggestions. When I put the old controller back, everything works perfectly except for the intermittent shifting.

At this point, I think the controller is faulty. If so, others should take note on how this controller can inadvertently cause the engine to run poorly.

First, the standard operation of the computer, start position and run position of the keyswitch
When one turns the key, several circuits are energized in the start position. (I don't care to elaborate but there are relays, etc.) This, in turn, applies 12 volts to one side of the coil for the relay for the starter. If the transmission is in Park or Neutral, the other side of the coil is grounded by the transmission computer and the relay coil will be energized thereby turning the starter. If the transmission is in one of the drive positions, when the key is turned, the other side of the coil goes into "unconnected" or high impedance mode from the transmission computer. In that case, there will be 12 volts on each side of the relay coil. Since no electrical potential difference, no coil activation therefor, no starter. In normal run mode, the keyswitch does not energize the circuits used for starting.


Here is my new theory.

Everything works properly with the replacement computer except for one thing. When the transmission is put into any of the drive positions, the output from the computer doesn't go into "unconnected" or high impedance mode. Instead, it outputs around 4.5 volts. This voltage backfeed is just enough energize some of the circuits which are enabled when one turns the key to the starting position.
One suggestion from the garage was to use the signal from the multipurpose switch (red) that would do what the computer output is doing. An additional problem is that there seems to be a voltage (4.5 volts) from the red multipurpose switch wire when in drive. When I did the bypass, this voltage energized the same circuits as the output of the computer.


The only way I was able to drive the vehicle with this condition was to hold my manual cold start switch.


There you go. Transmission computer affecting engine performance through the starter control wire!


Any thought or comments that I may have overlooked??


Mark
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Re: Lesharo automatic controller

Unread postby scott.edwards » Mon Aug 20, 2018 3:53 pm

Hi Mark,

You verified you have 12v going from the start position to the computer? Sometimes the fuse panel connections are poor, resulting in less that 12 volts, sometimes as low as 10 or 11 volts, which will not let the computer operate.

Or, the ground on the back of the computer (MPS) or on the engine itself is poor?

It's hard not being right there to help, so sorry if I am no help.

Cheers, Scott


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