From: mlschmidt@sprintmail.com [mailto:mlschmidt@sprintmail.com] Sent: Monday, July 08, 2002 1:41 PM To: 928 Subject: [928] RE: 1st to 2nd Shifts (Auto Tranny) >To get my kick-down switch to activate, >I have to press the pedal REALLY hard. There's an adjustment under the gas pedal that will fix that. It's a threaded piece that connects the gas pedal to the metal arm that depresses the kick down switch. Lengthening that connecting piece will cause the switch to activate without stepping on the pedal that hard. Mike Schmidt '88 928S4 Auto Black/Black "PORSCHE" cloth 928 Owners Club Charter Member PCA Chicago Region Subject: Re: Auto Trans Shifting From: GallantCSC@aol.com Date: Sat, 13 Feb 1999 13:09:03 EST X-Message-Number: 12 Sorry for the tardy reply. Regarding installation of the parallel kickdown switch for the auto trans: 1. The OEM kickdown switch is located under the throttle pedal, near the top, where the pedal can contact it when fully depressed. 2. By removing the floor pan carpeting first, and then pulling back the carpet from the bottom edge of the firewall, you can expose the KD switch wires. There are 2 going to the switch. 3. You will be placing another switch in parallel with the OEM switch, meaning a switch that goes between the 2 wires above. 4. One method is to cut the 2 wires (near the bottom, leaving room to work), strip all 4 ends, and crimp bullet connectors onto the 4 wires. If you are clever, you will install a male/female pair on each of the cut wires for the OEM switch so that if you remove the new switch later, you can just mate the cut wires together to restore the original OEM connection. 5. Make up a 2-wire cable by taking two pieces of insulated wire (18-gauge), twisting them together, and wrapping the whole thing with electrical tape to make a nice, easily manipulated cable. Strip the 2 wires on one end. 6. Now make 6 short pigtails, each comprising a short length of wire (a couple inches) with a bullet connector crimped on one end only. 7. Take 2 of these pigtails, strip the ends, and use a butt end crimp connector to mate them to one of the previously stripped wires of the cable. Do the same for the other wire of the cable. 8. Now plug these 4 connectors into the mating 4 connectors that you installed at the OEM KD switch. Note, the 2 pigtails on the same wire (a 'Y') get plugged into the 2 connectors from one cut wire, and the other 2 Y-connectors get plugged into the other pair of connectors from the other wire. 9. Now you need to purchase an appropriate switch and mount it somewhere. If you go to Radio Shack, you can buy any number of suitable switches. I used 2 types, a momentary, push-to-close type, and a push ON-push OFF type. 10. I mounted both of these switches on the driver's left foot support, near the very top. The momentary switch is mounted near the right edge of the foot rest, while the on/off switch is mounted a little higher up and more towards the left edge of the foot rest. 11. You can use the remaining 2 pigtails and solder these to the contacts on the switch. Then strip the other end of the cable you made, crimp on connectors, and plug into the switch. This allows you to remove the switch and the cable separately if you ever need to. 12. You don't need to mount the switches at the location described, anywhere you can reach the on/off switch will do, but the momentary switch, if used, needs to be activated while you are driving, so foot activation is preferable to finger activation, unless you can mount it to the steering wheel somehow. 13. So why did I use both types of switches? Well, sometimes I want to activate the KD continuously (for an autocross, let's say), while at other times, I just want to KD the tranny when I am requesting a little more go with the throttle. Before, unless I nailed the throttle very hard, it wouldn't downshift into a lower gear. By depressing the momentary switch (before or after depressing the throttle - it doesn't matter), the tranny will downshift into a lower gear with much less throttle input. So I do use both switches. 14. Note, don't expect you tranny to downshift when you engage the switch if you are just cruising around in steady-state. The closure of the switch only enables the KD solenoid in the tranny to engage (it does NOT directly activate the solenoid), it still requires other signals to do so (like more throttle for example). Also, the solenoid will not engage unless the engine rpm is sufficiently low so as to prevent overreving the engine if the downshift is made. 15. If this isn't clear, or if you need any other info, please let me know. Steve - 87S4/auto/GPW From: Wally Plumley [wplumley@bellsouth.net] Sent: Tuesday, July 24, 2001 10:03 PM To: 928 Subject: [928] Re: kickdown mod problem At 08:46 PM 7/24/01, Dennis Wilson wrote: >I recently tried doing the "kickdown switch modification" as documented on >many sites. Result was no discernable change in shifting behavior. >After checking my connections and ensuring the toggle switch is really >switching the circuit (probing continuity across the foot switch connector), >I'm fairly sure there is nothing wrong with my wiring job. That leaves me to >suspect faults in how this circuit is sending control signals to the AT. I >think I'm in for some under-car exploration... >Has anyone BTDT? I'm guessing there may be some kind of relay involved. >Anyone know how/where the kickdown circuit connects to the AT? >TIA dw As usual, it would have been nice to know the specific year model, but .... The automatic transmission is primarily controlled by internal hydraulic pressures. This includes the speed at which upshifts and downshifts occur, and the firmness of the shifts. The kickdown solenoid is only one of several devices that adjust the control pressure to change the shifts. When the kickdown switch is made (closed), power flows from fuse #10 (on the '87) thru the switch, then into the 30 terminal of the kickdown relay (XV on the '87), thru the normally closed contacts of the relay, and out the 87a terminal to the kickdown solenoid mounted inside the transmission. When the solenoid is energized, it reduces control pressure, raising the shift speed close to the maximum speed. The kickdown relay doesn't do what most people think that it does. The power flow from the switch to the solenoid is thru the NORMALLY CLOSED contacts of the relay. This means that the power normally flows thru the relay. In order to control the shift points more precisely (since the speed is very close to engine redline), the kickdown relay receives a signal from the tachometer when engine speed hits 5800 +/-60 RPM (USA and Japan - it's 100 RPM higher for the ROW). This signal open the contacts in the kickdown relay, breaking the power to the kickdown solenoid. This has the same effect as instantaneously lifting your foot from the throttle switch, causing an instant shift. As soon as the engine speed goes back below 5800, the relay closes the contacts, lowering the control pressure to hold the next shift. So, the kickdown switch (and the added parallel kickdown switch) supplies power to the kickdown solenoid only when the engine speed is below 5800 RPM. Above that speed, the kickdown relay opens, breaking the circuit. You can check by pulling relay XV (on the '87) and jumpering terminals 30 and 87a in the socket, then driving the car. If there is now a difference in the shift speeds, relay XV or the contacts for it are bad. I would suggest that you NOT try the full throttle shift points with the relay jumpered. Wally Plumley 928 Specialists -----Original Message----- From: Wally Plumley [mailto:wplumley@bellsouth.net] Sent: Thursday, December 19, 2002 11:07 PM To: 928 Subject: [928] Re: Kick down doesn't work after torque tube project Park next to a wall in a quiet place, or in your garage. Roll the windows down. Turn the ignition on. Press the throttle hard to the floor while listening for a click. If you hear the click as the throttle switch engages, look at the cable adjustment. If there is no click, check fuse #10. If the fuse is good, pull the transmission connector off and put a test light from the wire to ground. Ignition on, press throttle pedal. If there is a light, the problem is the connection. If no light, check the switch. If the power is good thru the switch, check relay XV by jumpering from terminal 30 to terminal 87 in the socket and checking for the click or light at the transmission. Wally Plumley 928 Specialists