Relays

[gcw206]

Hello,

1969 280SE W111 Coupe, A/C, power windows.
I have 3 relays on the firewall directly in front of the driver.
The center one is the CSV, I need to know what the other 2 are used for.
(There are 2 on the passenger side of the firewall, but they are for the power windows.)
Thank you,

GCW

[wwheeler]

Are these 4 pole of 5 pole relays? One is typically for the starting solenoid on the IP. Does your IP have two solenoids or just one? Starting solenoids are shorter than the US emission solenoid. The tech manual will have something on this. One could be for A/C, not sure. I don't have A/C, so can't say.

[lpeterssen]

Dear friend

Wallace is right,  the relays on the firewall on w111, mostly manage the cold start logic of your car. One as you already discovered is for the CSV (cold start valve), the other element in the cold start logic is the Mixture magnet at the Injection pump (IP). The Mixture magnet is on its enrichment position for all the time you crank your engine up to 10 consecutive seconds or whenever engine temperature is lower than 35 degrees Celsius (depending on the TTS installed could be a different set point).  The third relay could be the Time relay to control for how long the CSV is active during the cranking. (Usually just 1 second). Cylindrical shape.  On very old w111 also there is a cylindrical silver relay responsible of the blinkers (flasher/turn signals)

Another two possibilities for the third relay are:

A. A high beam low beam relay (if it has 5 poles)
B. A time  delay relay for dome lights (is like a flat cylindrical can, brand VDO)

It is better to have a picture and unplug each of the connectors, take the cover out of them and see the colors of the cables coming to each relay. In that way you can identify with no doubt the service /function of each of them.  Of course you need a wiring diagram.

Use the diagram for Mercedes pagoda W113sl-280SL which is quite similar for that part.

Best regards
L.peterssen

[col320ce]

Mine had oval one time relay for starting, csv, wipers, ip solenoid.
It's a rhd without power windows.

[wwheeler]

The earlier cars had the round one second timer, but GCW's W111 is a '69 I think.

Speaking of wiper relays, do W111s have those? If my '68 has one, I sure don't know where it is. I know the W113s have one. It can't be in the engine compartment because I know ever square inch of that space. Could it be under the dash? Why would the W113s have it and the W111s don't?

[lpeterssen]

Wallace

W111 do not have wiper relays as the ones we see on the fender of the w113.  W111 have a foot wiper pump switch which is referred sometimes as a relay, but it is not really one.  It is just a switch which commutes the connection of the cable attached to that plug.  In one position the two upper cables are connected together, and in the other position the other two cables make continuity.

It’s function is to send energy to wiper motor each time you press the pump.

Best regards
L.p

[wwheeler]

Thanks! That answers that!