Clutch Switch Bypass For Big Blue

[Gary Lewis]

Got to test the 10 second delay module today, and it works perfectly - as you can see in the video below.

So now I need to find a 2V panel-mount LED to replace or parallel the one you can see on the board to tell the driver he can crank it then.

[Gary Lewis]

I found that I can't measure the on-board LED's current.  So I took it off the board and stuck the lowest-current LED I could find in my stock and that pulled 4ma and just barely glowed.  

So I'm going to have to come up with a Plan B for an LED to indicate when the bypass is active.  

[Gary Lewis]

Ok, here's Plan B.  Please pick it apart.  

The trigger circuit nor the coil are drawn in, but you'll get the gist.  The LED will be energized with the key on, but won't have a ground until the relay closes and then it'll use the starter relay's coil and the ignition box as the ground.  So it'll go out, or seriously dim, when the starter is engaged.  But it'll glow bright red when the clutch safety is bypassed.

[Nothing Special]

Sounds like it will work.  but do you need the indicator?  If it's going to go out in 10 seconds it's not like you need a reminder to turn it off.  I suppose it could be nice to know that you actually pushed the button, and to know when it times out so you need to push it again (if you're not done with it yet).  But those don't seem all that necessary either.

Or maybe you just need it because YOU just need it!  That's OK too!

[Gary Lewis]

I think it is the latter - I want it.  

Was playing with MyBB forum software the other day and it requires you to attach a picture to a post and then click a button to put the picture in the post you are writing.  There's no feedback on the button and you can't see the text of the post at that point, so the first time I used it I clicked the button three times and had three copies in the post.

I like feedback.  When I push a button I want to know that something happened.  And the LED coming on will tell me that something happened.  Plus it'll tell me if the thing timed out and I have to hit it again.

By the way, you can hold the button in as long as you want and the relay stays closed.  But when you let up after more than 10 seconds the relay drops out.  In other words, it is the first push that starts the timer.

And to document my thinking & calculating, the LED will drop about 2 volts, so the resistor needs to drop ~10v @ 30ma.  R = E/I = 10/.03 = 333.  But that's a non-standard number so it'll probably be a 330 ohm resistor.  And that should be an orange/orange/brown resistor.

[85lebaront2]

I realize this might be entirely too simple for you, but, I assume that the conditions under which you would need this would be (a) off road, probably rock or similar crawling (b) in 4WD low range and 1st gear in the ZF. (c) one hand on the wheel and the other on the shifter.

If it were me, I would put a key switch on the dash with a warning light reading "starter safety bypassed", this switch would be a double pole single throw normally off. One side would jumper the clutch safety, the other turn on the light. A push button switch on the shifter to activate the starter, sort of like the splitter control on the big rig transmissions. This way both hands stay where they are needed.

[Gary Lewis]

Thanks, Bill.  You are right, those are the conditions in which I'd be wanting to bypass the clutch safety switch.  And your setup would get the desired result of being able to crank w/o pushing in the clutch and having one hand on the wheel.  (It would require one hand on the shift lever to be pushing the start switch.)

My approach accomplishes the same thing - left hand pushes the bypass button and then moves to the steering wheel while the right hand turns the key to Start.  But yours is more robust as it is mechanical rather than electronic.

Thanks, but I'll continue on which my plan and fall back to something else if it doesn't work.

[85lebaront2]

I have long been a fan of the KISS theory, "Keep It Simple Stupid".

[Gary Lewis]

Let's see, EFI with MAF & SEFI are KISS when compared to a carb?  An E4OD is simpler than a C6?  

I think it is too late for KISS on Big Blue.  

[85lebaront2]

How many times did you change metering rods or jets in your AFBs or WCFBs? How many vacuum modulators have you replaced on C4, C6 or GM TH models.

Ok, answer this, you want to improve the shift quality on your C6, or maybe even a Torqueflite 727. What else does it affect? Now do this on an E4OD, 4R70W, 4L80E. All of these the line pressure can be altered without changing the shift points.

Think of an EEC-V as using AI to adjust things on the fly, like altitude changes. It is a lot simpler once set up.

[Gary Lewis]

Hey, I'm not the one saying Keep It Simple, Stupid.  I agree with you that it is lots easier to tune the EFI to 14.9 AFR with BE than to swap jets on an AFB.  (Yes, I know that swapping rods is easy, but there is only so much you can do with rods before needing to swap jets.)  And the AFR stays where it is supposed to be instead of leaning out as you ease into it before the rods pop up.

And vacuum modulators are frequently the issue, not just on C6's or 727s, but on a Powerglides as well.  I remember so well when I was at K-State and came down with mono during finals.  A buddy drove my 58 Belaire to Newton where my mother took over.  But it wasn't shifting right and she wanted to know why.  "Vacuum modulator, Mom.  I'll change it out when I get over this crud."

So I'm happy with the tech I/we've installed.  Just need to move on to Dad's truck and pick your brain on the E4OD setup.  Maybe even clone your tune but tell it I have a 400 instead of a 460.

[Nothing Special]

85lebaront2 wrote

... I assume that the conditions under which you would need this would be (a) off road, probably rock or similar crawling (b) in 4WD low range and 1st gear in the ZF. (c) one hand on the wheel and the other on the shifter....

You generally don't need a hand on the shifter when doing this.  You're in low-low and you're going to stay there, at least until the engine is started.

Having at least one hand on the steering wheel is important, and if you could have 2 it would be better (no power steering while cranking the engine).  Early Jeeps had the starter switch on the floor, which did allow 2 hands on the wheel.

[Gary Lewis]

Time for an update.  (I've been a bit busy with other things, including trying to find and implement a new forum platform.)

I got the panel-mount LEDs and the time-delay relay in a couple of days ago and just had a chance to test both of them.

On the left is the test of the LED, and while I'd guessed that a 330 ohm resistor would be correct, it turns out that a 560 drops it from 14V such that the LED is pulling its rated 30ma.  And while it might look pale in the pic, it is quite bright and will get your attention, even in bright sunshine.

And on the right are the two modules as well as the LED and pushbutton.  I think I'm going with the Bosh-style unit since it will be easier to deal with.  I'll just terminate all the wires with 1/4" female connectors, glue a tab on the back, and stick it under the dash.

Now I need to sort the wiring diagram.  

[Gary Lewis]

Well, phooey!  That's not going to work.  The Bosch-style relay is wired where it puts 12V on the output instead of giving a contact closure.  So it would crank the engine for 10 seconds instead of just bypassing the clutch switch.  

So we are back to the module with the printed circuit board.  I have a case to put it in, so now I just need to draw up the wiring.  

[Gary Lewis]

Not making much progress, but some.  I pulled the AFR meter's bezel off today thinking I'd disconnect the meter and work on the bezel.  But there's a lot of wiring that would have to be fed back through things up under the dash in order to get the gauge out.  So either I find another home for the switch and the LED or just drill the bezel in place for the LED and the switch.

Then I wired the relay board up to pull in a fender-style starter relay and it wouldn't do it.  Turns out they apparently put the on-board LED in the on-board relay's coil circuit.  And since I'd removed that LED the relay wasn't coming in.  But when I wired in another LED the on-board relay came in just fine and it pulled the starter relay in.

However, the clack that starter relay made suggested I find out how much current it is pulling 'cause it sounded like a lot.  Turns out it is "only" 3.5 amps, which is well within the 10A capability of the on-board relay.

But that got me to wondering what kind of back EMF that starter relay generates and what problems it might cause.  I tried to measure it with my min/max DVM but it didn't seem to catch it, and I was loathe to drag out the 'scope.  So instead I dragged out the left over 10A diodes that I bought when I put one on the air conditioning compressor's clutch to protect the ECU, and made one to fit Big Blue's starter relay.  You can see it, the snubber diode, in the bottom center of the pic on the right.

But as I started to pull the nut that holds the trigger wire on the starter relay it occurred to me that the nut & stud right above it was hot, and touching the socket to either of them while on the trigger stud would engage the starter.  And while the tranny was in neutral and the park brake set it would have caused a quick reaction on my part, so I pulled the starter relay fuse out of the PDB and worked w/o surprise.

[Nothing Special]

Progress!

[Gary Lewis]

Thanks, Bob.  Yes, it is progress, but not as much as I'd planned for the day.  Had hoped to get the AFR gauge bezel off so I could drill it on the bench and the PC it black like the bezel on the other side.  But that's not going to happen.

So now I'm wondering if I can drill it in the truck and leave it chrome.  Luckily I've not ordered the clear/white tape for my Brother label maker as if I leave it chrome it'll need to be clear/black tape.

I have a work day at the church building tomorrow, so maybe Wednesday I can see how to do that.

[Gary Lewis]

Well, it is time for an update and to quit for the day 'cause two steps forward and three backwards ain't progress.  

Here's what I did:

Plus 1: First, I drilled the holes in the AFR meter's bezel for the LED and the switch.  That went well and I got the switch mounted, as you can see below.

Minus 1: Then I decided I'd see if there was a way to wire the LED to make it brighter than what the 4 ma it gets through the "remote" arrangement I wired up by removing the LED from the board and soldering wires to the board.  Not only did I not find a better way I blew up one of the three LEDs I bought.

Minus 1: But since the LED is in the relay's coil circuit it has to be there, I decided to just put an LED on those remote wires and leave it in the box I mount the module in and wire the LED on the panel such that it uses the starter relay's coil as ground..  Got an LED all soldered up and decided I ought to put hot-melt on the board to ensure the wires don't come off, after which the module wouldn't work.  So a new one arrives tomorrow.

Plus 1: Then I revised the schematic and that let me figure out how to wire the LED on the panel without another connector.

Minus 1: So, why not wire up the new LED with the ballast resistor in the circuit?  Better make sure it'll go through the hole in the bezel.  It did, including the heat-shrink tubing but when I tried to get the nut off the LED it won't go over the resistor.  

[Gary Lewis]

Well, yesterday wasn't quite as bad as I thought.  I got to wondering how much larger the lead for the LED is vs the nut since the lock washer goes over it easily.  Turns out it was only .010" larger, so it threaded itself on fairly easily, as shown below.

So that let me mount in the bezel and then mount the bezel on the dash, and then secure the meter in the bezel - in that order.  (You can't get to the screws to mount the bezel on the dash with the gauge secured in the bezel.)  And then I hooked the LED up to my test battery for the shot below.

The new timer module is supposed to be delivered later today, so maybe tomorrow afternoon or Tuesday I'll get to that part of the project.  I have to cut holes in the box for the wires to go through, then glue the module in the box, wire it up, and install it.

[viven44]

Clean wiring job! As expected from you.

By the way, is that a fuel efficiency meter ? How does it work ? Any special computer needed ?