Steve Cattaneo

A fully charged automotive car battery is not 12volts; if you have a 12V reading the battery is dead. Confirm a fully charged battery, minimum 12.4volts, and test for 12.4 volts at terminal #2 of the 5pole connector in the spare tire well then at the black wire which plugs into the solenoid. On both tests use the battery neg. terminal for ground then the transmission case as a ground point to identify a bad body ground. Check the fuse; Kick down relay terminals and terminal # 2 of the 5pole connector in the spare tire well for corrosion and clean if necessary.



To eliminate a defective relay, remove it and jump terminals # 30 to #87A with a jumper wire with a 15amp spade fuse ran in series for protection, then active the kick down switch under the gas pedal and confirm your voltage at terminal #2 of the 5pole connector in the spare tire well, and the black wire which plugs into the solenoid.



Fuse #10 provides battery voltage to the kick down switch under the gas pedal, when closed power out is a gray / brown stripe wire feeding terminal #30 of the Kick down relay XV, exits at terminal #87A supplying power to the KD solenoid through terminal #2 of the 5pole connector in the spare tire well, then down to the solenoid.

The Kick down solenoid only has one terminal; the injector body provides the ground thru case.

solenoid 1

solenoid 2
12.70 / 6.35 100% 1.265+
12.45 / 6.23 75% 1.225
12.24 / 6.12 50% 1.190
12.06 / 6.03 25% 1.155
11.89 / 5.95

S4-on-your-back-door

mine has 2 poles and the connector slips over them and than has a rubber boot that has a collar that screws the boot over the connector and onto the solenoid

Steve Cattaneo

What you described is not the Kick down solenoid; it’s the transmission overload protection switch installed in S4, GT and GTS transmissions, it has a brass ring. The kick down solenoid on every 722.3 (4speed) transmission used in 928s and Mercedes Benz looks like the picture I posted. Located on the passenger side tail of the transmission.

S4-on-your-back-door

well then,i installed that on the 85 trans that is in the car now, so that is not the kickdown solenoid hmm, i guess the trans is protected now lol now i'll hav to recheck rite solenoid for voltage. but i still didnt here any click when jumping switch out. also i notice that at 80mph or greater trans will not drop into third, but under 80 say 79 it will any thoughts remember its an 85 trans.

Steve Cattaneo

down shifting or upshifting.


Locate the kick down solenoid, passenger’s side rear of the transmission; make sure the Black wire is plugged in. if so, then turn the ignition on, passenger side door open depress the kick down solenoid switch under the gas pedal with your hand, the switch and the solenoid should click.

If the KD switch under the pedal does not click, it’s stuck on or defective, replace it, and or you have no power going to the switch, check the fuse. If it clicks by hand and not with the gas pedal, adjusts the pedal so it makes contact with the switch, once fixed, the kick down solenoid in the rear of the transmission should click, if no follow the diagnostic procedure in my previous post. The 85 transmission has the same kick down solenoid as in the 87 transmission.