Gary Lewis Posted June 11, 2023 Share Posted June 11, 2023 Are the red letters saying "Circuit Opened If Clutch Pedal Released (Up)" yours or in the instructions. The red text is mine. I tested the Clutch Switch and was surprised to discover that it is a "normal opened circuit" until the pedal is depressed. Then (clutch released, pedal to the floor), the switch closes the circuit, enabling a depressed Brake pedal to send 12V to the Brake Lights and, therefore to the Speed Control Module. That appears to be completely backwards from what I expected. But maybe I'm missing something. I'd go ahead and install it the way the instructions say and find out how/if it works. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted June 11, 2023 Author Share Posted June 11, 2023 Jeff - I'm confused as well. The schematic below, from the 1985 EVTM, shows how Ford did it. Are the red letters saying "Circuit Opened If Clutch Pedal Released (Up)" yours or in the instructions. They appear to be exactly backwards. If the switch closed when the clutch pedal is up, meaning the clutch is engaged, then the speed control system would "see" the brake lamp. So if they were to put a pull-up resistor on that wire the voltage would be showing 0V since the brake lamp has a very low resistance. Then if the clutch pedal is depressed the voltage would go up to 12V. Or if the brake pedal is depressed the voltage would also go to 12V. Gary, I'll test again this morning the Clutch Switch, to confirm its behavior. We'll see. But about the action of the Clutch Switch (normally opened or not, I'll test again), I do not understand the «or» in your sentence and in the Dealer Installed Speed Control instructions: This implies that, whichever of the brake or clutch pedal is depressed, a 12V signal goes to the SC Module. However, the Clutch Switch is linked to the cold side of the Brake Switch... How can it send a 12V signal while the Brake Switch is cutting the circuit? http://www.garysgaragemahal.com/uploads/6/5/8/7/65879365/thinking-26_orig.jpg Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 11, 2023 Share Posted June 11, 2023 Gary, I'll test again this morning the Clutch Switch, to confirm its behavior. We'll see. But about the action of the Clutch Switch (normally opened or not, I'll test again), I do not understand the «or» in your sentence and in the Dealer Installed Speed Control instructions: This implies that, whichever of the brake or clutch pedal is depressed, a 12V signal goes to the SC Module. However, the Clutch Switch is linked to the cold side of the Brake Switch... How can it send a 12V signal while the Brake Switch is cutting the circuit? Let's say it a different way. If I were doing it I'd put a pull-up resistor of maybe 2000 ohms on the green wire that is going to the cruise control master harness. And assuming the clutch switch is closed when the clutch is engaged, meaning the pedal is up, the voltage going to the cruise control would normally be 0 volts because it would be held down by the brake light, which is a low-ohm resistor. But, in these conditions the voltage would go to battery voltage: Clutch Disengaged/Brake Off: When the clutch is disengaged the cruise control will "see" battery voltage on the green wire because the clutch switch opens and the brake light bulb is no longer grounding it. So the 2K ohm pull-up resistor will take the input "high". Clutch Engaged/Brake Engaged: When the brake switch closes the voltage the cruise control will see battery voltage because the brake switch puts battery voltage to the bulb and since the clutch switch is closed that voltage will go right on to the module. Clutch Disengaged/Brake Engaged: Even in this condition the module will see 12V because with the clutch switch open the pull-up resistor takes the input high. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted June 11, 2023 Author Share Posted June 11, 2023 That appears to be completely backwards from what I expected. Gary, about the Clutch Switch «normally opened» or «normally closed», mystery solved. The NOS E4ZZ-9A819-A - Manual Transmission Clutch Switch I bought (sealed in original Ford package) can be wired in ether of these two behaviors! This is far to be idiot proof! I wrongly presumed that the two metal blades on the same side were simply a "split"of the same terminal. In fact, one is normally opened and the other normally closed. https://youtube.com/shorts/ZaUskBverC8?feature=share But Gary, this doesn't solve my "or" questioning, still not clear for me. Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 11, 2023 Share Posted June 11, 2023 That appears to be completely backwards from what I expected. Gary, about the Clutch Switch «normally opened» or «normally closed», mystery solved. The NOS E4ZZ-9A819-A - Manual Transmission Clutch Switch I bought (sealed in original Ford package) can be wired in ether of these two behaviors! This is far to be idiot proof! I wrongly presumed that the two metal blades on the same side were simply a "split"of the same terminal. In fact, one is normally opened and the other normally closed. https://youtube.com/shorts/ZaUskBverC8?feature=share But Gary, this doesn't solve my "or" questioning, still not clear for me. I'll address the "or" this afternoon, after church. But please read my latest post again where I thought I addressed "or". Link to comment Share on other sites More sharing options...
BigBrother-84 Posted June 11, 2023 Author Share Posted June 11, 2023 This is far to be idiot proof Well, I have to apologize... Guys at Ford did it idiot proof. The connector is wired to one of the two twin blades, the other one is left blank: Clutch Pedal released (up): Circuit normally closed: Clutch Pedal depressed (to the floor): Circuit opened: Gary, about the "or" question, I read you but still don't understand how depressing only the clutch pedal (without touching the brake pedal) could send a 12V signal to the SC Module. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted June 11, 2023 Author Share Posted June 11, 2023 Let's say it a different way. If I were doing it I'd put a pull-up resistor of maybe 2000 ohms on the green wire that is going to the cruise control master harness. And assuming the clutch switch is closed when the clutch is engaged, meaning the pedal is up, the voltage going to the cruise control would normally be 0 volts because it would be held down by the brake light, which is a low-ohm resistor. But, in these conditions the voltage would go to battery voltage: Clutch Disengaged/Brake Off: When the clutch is disengaged the cruise control will "see" battery voltage on the green wire because the clutch switch opens and the brake light bulb is no longer grounding it. So the 2K ohm pull-up resistor will take the input "high". Clutch Engaged/Brake Engaged: When the brake switch closes the voltage the cruise control will see battery voltage because the brake switch puts battery voltage to the bulb and since the clutch switch is closed that voltage will go right on to the module. Clutch Disengaged/Brake Engaged: Even in this condition the module will see 12V because with the clutch switch open the pull-up resistor takes the input high. Ok, I draw a simple circuit: • With the Clutch Switch closed (normal position, pedal up), the SC Module "sees" the ground bulb light. • If clutch pedal is depressed, the Clutch Switch opens and the SC Module sees that it doesn't see the ground bulb anymore, and so understand that clutch pedal is being depressed. I was wrong assuming that the green wire was a simple "ground" one. Somehow, the SC Module is reading at the green wire, this wire isn't a + or - one. It is a "listening" one. Am I understanding correctly? If so, a non functional SC could warn the driver that brake light bulbs are burned up... http://www.garysgaragemahal.com/uploads/6/5/8/7/65879365/thinking-26_orig.jpg Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 11, 2023 Share Posted June 11, 2023 Ok, I draw a simple circuit: • With the Clutch Switch closed (normal position, pedal up), the SC Module "sees" the ground bulb light. • If clutch pedal is depressed, the Clutch Switch opens and the SC Module sees that it doesn't see the ground bulb anymore, and so understand that clutch pedal is being depressed. I was wrong assuming that the green wire was a simple "ground" one. Somehow, the SC Module is reading at the green wire, this wire isn't a + or - one. It is a "listening" one. Am I understanding correctly? If so, a non functional SC could warn the driver that brake light bulbs are burned up... http://www.garysgaragemahal.com/uploads/6/5/8/7/65879365/thinking-26_orig.jpg I think you have it worked out. But let me say it differently. First, I think the module has a pull-up resistor in it, as I've added to your drawing. And the module is looking to see if the input is at ground or battery voltage. So if the clutch switch is closed and the brake is off it'll be at ground - if there is a good brake light bulb in the circuit. (You are right, if the speed control doesn't work you should check the brake light bulbs.) And ground lets the speed control work. But if the clutch switch is closed and the brake switch is closed it'll be at battery voltage. Or if the clutch switch is open, regardless of the brake switch position, it'll be at battery voltage. And if the input is at battery voltage the speed control will not work. Does that answer the question? Link to comment Share on other sites More sharing options...
BigBrother-84 Posted June 11, 2023 Author Share Posted June 11, 2023 Does that answer the question? https://forum.garysgaragemahal.com/file/n136799/Cruise_Control_Pull-Up_Resistor.jpg Oh yeah, thanks so much! I hate to blindly follow instructions without understanding what I'm doing. I would say that all the SC system was becoming clear for me, except this famous Clutch Switch. So, you can imagine my surprise when I tested this switch and discovered it was acting reversely than expected! I was completely lost... I should have followed the instructions a little bit farther, plugged the connector and then tested it from the wires end. I apologize for the fling-flang I caused! Link to comment Share on other sites More sharing options...
Gary Lewis Posted June 11, 2023 Share Posted June 11, 2023 Does that answer the question? https://forum.garysgaragemahal.com/file/n136799/Cruise_Control_Pull-Up_Resistor.jpg Oh yeah, thanks so much! I hate to blindly follow instructions without understanding what I'm doing. I would say that all the SC system was becoming clear for me, except this famous Clutch Switch. So, you can imagine my surprise when I tested this switch and discovered it was acting reversely than expected! I was completely lost... I should have followed the instructions a little bit farther, plugged the connector and then tested it from the wires end. I apologize for the fling-flang I caused! No problem at all! I was happy to work through the circuits to see how they might work. Kind of like solving a puzzle. And I do understand wanting to have your head around how something works before installing it. I do the same. Link to comment Share on other sites More sharing options...
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