Relays? Again?

[TEJOLX47]

Hi guys,

Remember about the 4th relay?
Well, I got there... but it doesn't "match" what seems to be in my car.
Step by step:
1. I have a CSV relay; once we start the engine, if the temperature is low, it activates the relay that, in turn, activates the CSV.
2. I don't seem to have a FIP relay... that seems to be my problem;
3. I have a wiper relay; working properly.

Then what do I have?
A strange combination: In fact, I have two relays (4 pole) mounted together. Are they perhaps the combination of the FIP and the famous 4th relay?
From my investigation, the following wires connect to the set of relay's:
a. Hot wire (from battery);
b. A wire coming from the "Relay box" of the Emission Control System; I suspect it brings power from the transmissions solenoids;
c. A wire coming from the ignition;
d. A wire going to the "Constant speed solenoid";
e. A ground wire;
f. There are also two wires that connect one relay to the other;
Apparently, the only thing that this pair of relays "does", is to energize the "Constant speed solenoid". That is the reason I suspect that wire b. is the one coming from the transmission solenoids.

Coming back to the FIP relay, the only wire I see going to the FIP is one coming out of the "Working current relay" of the Emission Control System. That was expected.

Can anyone shad some light on the subject?
Key questions I would like to have an answer for:
I. Is there a FIP relay on other cars? If so, what is its purpose?
II. I know the "Constant speed solenoid" is supposed to be activated by the transmission solenoids; does it happen via the "Relay box" of the Emission Control System? If so, how is the "Constant speed solenoid" activated in European cars (without Emission Control System)?
Thanks in advance.
Francisco

[mrfatboy]

The relay in question in your picture (most forward towards front of car) should be the fuel cutoff relay that is connected to the bottom solenoid of the FIP.  At least it is on mine.

Do you have two solenoids on the back of your FIP?  One?

You have a later car then mine and I know changes were made.  I'm sure the experts can shed more light.

[teahead]

I dont' have that "?" relay.  At least, not where your's is at.

I have the same year car (see signature).

Interesting.

[TEJOLX47]

Hi mrfatboy,
My car is a 1970 USA 280 SL
So, to answer you question, my FIP has a cut-off solenoid. It is activated by the Working current relay, one of the four components of the Emission control system that my car has.
In regards to the picture, I only have the wipers relay and the CSV relay.
Cheers

[TEJOLX47]

Hi teahead,

Thanks for the answer.
My car is also a 1970 280SL, VIN ending 021859.
I have the CSV and the wipers relays, but I miss the FIP and the ”?”.
Do you know where you FIP relay (second from firewall) connects?
Thanks
F

PS: the picture is from the Manual of SL113.org

[teahead]

Hah! Thought it was your car.

I need to look at mine on what all I have.

Regarding the CSS, I don't think it has a relay.  On your car, which is same as mine, my CSS isn't even hooked up.  I guess to raise idle when in gear, they rely on the dashpot, which I really don't like as it seems to run rougher with that and does little to raise the idle.

When the dealer added AC to my car (I assume they did), guess they forgot to do something w/the CSS.  Regardless, when I put on the AC, the idle hardly drops at all.  Again, my biggest drop in idle is putting my car in gear (auto trans of course here).

[TEJOLX47]

Hi teahead,

The two odd relays I have near the CSV relay are modern relays and, together, they activate the CSS.
However, I still have to check if they work properly when D or R is activated.
I intend to test it tomorrow.
As to the AC which I also have, they should have linked a wire from the compressor to the CSS in order to adjust the idle. Mine has also no connection at all.
More to know...
Cheers

[Pawel66]

In my car (1970 euro automatic) I have same two 4 pin relays one next to the other. One is for FIP solenoid (cold start, not cut-off), one for CSV, they are also connected. Funny thing is that my FIP (R25) does not have the solenoid. But the relay is there, the wire goes towards where the solenoid on FIP would be and it ends tied to one of the lines that are there.

I figured it by following this wire to the end.

So there are wire and relay, but no solenoid. I have a spare relay, in essence...

The CSS, to answer your question, in Euro wiring for automatic, is activated by ground delivered from either of the two hydraulic switched located on both sides, at the bottom of the transmission. One switch for Reverse, one for Drive. The green/red wire goes from right hand side switch, over the tranny, meet at the conatct plate with the other wire from the left hand side switch and go to CSS. + is delivered to CSS from fuse No. 3.

I do not have AC, I do not know the Euro solution with automatic and AC.

[ja17]

Some relay plugs and wires will reach different relays. So someone can accidentally switch plugs going to some relays. No big deal since the relays are the same, but you may have difficulty figuring which relay is for what. The solution is simple. Unplug the relay, energize #87 socket of the plug and you will hear the device that particular relay operates. I keep a spare relay in my tool box. It has the cover removed. For testing I simply turn the ignition on, remove the relay in question, replace it with my test relay and manually press the relay, causing the device to activate and identify itself.

[TEJOLX47]

Dear Joe, Pawel, teahead and mrfatboy,

Thank you all for your comments.
After extensive digging on the car and some search on the 280 SL USA wiring diagram, I have reached the following conclusions about my car.
1. The wires from my transmission solenoids do not feed the CSS (Constant speed solenoid); instead they go to the Relay Box on the Emission control system (and that is correct according to the wiring diagram of the Relay Box - pin 1 on #33 is activated by #36);
2. I have no FIP relay on my car; instead FIP gets deactivated by the Working current relay on the Emission control system, under specific circumstances (and that is correct according to the wiring diagram - relay #49 when activated feeds #59);
3. I have a normal CSV relay, that helps ignition bellow certain temperatures;
4. I have a wiper relay;
5. I also have two (modern plastic) relays  linked together (I belied the word is shunted), that will activate the CSS (Constant speed solenoid) if there is power in the ignition and power on any of the Transmission solenoids (use the suggestion of Joe to test the relay result). They work properly (when transmission engaged) although I believe this is not the original solution.
To make life easier, I will keep it the way it is once these relays are out of sight. Should you know better the way to fix it, suggestions will be welcome.

Finally, I have been reading the wiring diagram were there is no CSV (Constant speed solenoid) anywhere but there is something called Idle Increase Solenoid (#51) that I believe to be the same component. Interestingly, this solenoid - as per the diagram - is activated by the kick-down switch ("53) and the Venturi control unit switch (#54) together.

Please use them to compare but not to copy to your cars... once I don't know this is the correct configuration.
Thank again for all the opinion's and suggestions.
Cheers
Francisco

[Pawel66]

Great you figured it out!

Just fo rmy learning:

1. "will activate the CSS (Constant speed solenoid) if there is power in the ignition and power on any of the Transmission solenoids (use the suggestion of Joe to test the relay result). They work properly (when transmission engaged) although I believe this is not the original solution." Which transmission solenoids do you mean? I think there is one three-way solenoid on transmission. You mean any of the connectors on this solenoid or you call "solenoids" the two hydraulic switches? This is interesting - that is why I ask. In view of price of these hydraulic switches, any smart solution on activating of the CSS is ov value...

2. I certainly do not know for sure, but it feels like 51 description is wrong and it is the three-way solenoid on gear box. This is the US diagram, I am not sure CSS is there at all.

[teahead]

"5. I also have two (modern plastic) relays  linked together (I belied the word is shunted), that will activate the CSS (Constant speed solenoid) if there is power in the ignition and power on any of the Transmission solenoids (use the suggestion of Joe to test the relay result). They work properly (when transmission engaged) although I believe this is not the original solution."

Ya, that sounds to me like a homemade solution.

Does it actually work?  In conjunction w/your dashpot and slip joint?

[TEJOLX47]

Great you figured it out!

Just fo rmy learning:

1. "will activate the CSS (Constant speed solenoid) if there is power in the ignition and power on any of the Transmission solenoids (use the suggestion of Joe to test the relay result). They work properly (when transmission engaged) although I believe this is not the original solution." Which transmission solenoids do you mean? I think there is one three-way solenoid on transmission. You mean any of the connectors on this solenoid or you call "solenoids" the two hydraulic switches? This is interesting - that is why I ask. In view of price of these hydraulic switches, any smart solution on activating of the CSS is ov value...

2. I certainly do not know for sure, but it feels like 51 description is wrong and it is the three-way solenoid on gear box. This is the US diagram, I am not sure CSS is there at all.

In fact, some people call solenóides to the pressure switches on the transmission (part # A 0015421317].
As to the 3 position solenoid in the auto transmission, I believe it only affects the gearbox itself and nothing outside the gearbox.
Your view on #51 is interesting. I will go back to the diagram to exploit that view.
Cheers

[TEJOLX47]

"5. I also have two (modern plastic) relays  linked together (I belied the word is shunted), that will activate the CSS (Constant speed solenoid) if there is power in the ignition and power on any of the Transmission solenoids (use the suggestion of Joe to test the relay result). They work properly (when transmission engaged) although I believe this is not the original solution."

Ya, that sounds to me like a homemade solution.

Does it actually work?  In conjunction w/your dashpot and slip joint?

Teahead,

I have no dashpot nor slipjoint.
Correction of rpm is made via the Constant speed solenoid, which consists of a rod that pushes the accelerator forward when a solenoid is activated.
Only that in my car.
Cheers
F

[ja17]

Francisco, you might be reading your wiring diagram wrong. The venture switch and kickdown are related to the solenoid on the transmission.

[Pawel66]

I think the description of item 51 may be wrong on the diagram.

[TEJOLX47]

Francisco, you might be reading your wiring diagram wrong. The venture switch and kickdown are related to the solenoid on the transmission.

You are right.
Thanks and apologies for the late answer
Cheers

[Philippe VIARD]

Good morning,
I have a 280 sl euro 70 delivered new in France with manual transmission without AC. The electrical harness is original. The FIP is type R25 whihout solenoid
Like Pawell66, I have 3 relays close to the left fender (cf photo) but one of them is different.
You can see right to left on the picture wiper relay, relay for csv on the middle and the third.
The third is a Bosch relay ref 0332 200 009 with 5 flat pins. The electrical connections on the pins are screwed.
pin 85 : wire brawn  pin 86 : wire yellow /grey
pin 30/51 : wire white/violet
pin 87: wire yellow  pin 87a: wire white
The relay receives no current at pin 30.
I see no correspondence with the electricalscheme 280sl august 70 but on the wiring diagram of model 280se we can see a relay with 5 pins for optional extra air conditioning (36) but there is not wire to the 87 pin.
Do you have some idea?
viard

[Pawel66]

The different one is for wipers. It controls the work of the wipers.

By the way: one of your 4 pin relays has the rubber mounting buffers, the other one does not. These buffers can be bought here:

https://www.sls-hh-shop.de/main/en/mercedes-230-280sl-w113-/15-electrical-equipment-at-engine/07-c-electric-engine-control/rubbermount-relais-p-5639

[Philippe VIARD]

Dear Pawel66,
the wiper relay is well identified on the rigth of the photo with an inscription "essuie glace".
The interrogation is abaout the left relay on the picture.

[Pawel66]

One of these two relays operates CSV, the other one the mixture control solenoid on the fuel injection pump (I can never remember which is which, I think the one closer to the wiper relay is the one that operates solenoid on FIP, not sure). I assume you have 280SL where these relays are wired together, if you look underneath at the harnesses you will see they are connected.

They get signal from the wire that goes to starter, so they work when you crank the engine only. The other part of signal comes from the Thermo Time Switch. One relay switches on the CSV, the other one switches on the solenoid on FIP. They supply power (+) to both components. It is clearly shown on the coloured wiring diagram we have in our Technical Manual (components 20 and 21, CSV is 31 and FIP solenoid is 33).

I was writing above that, since my car is an Euro car, I do not have the mixture control solenoid on FIP, so the wire from the relay controlling this solenoid is just not connected.

[lpeterssen]

Good morning,
I have a 280 sl euro 70 delivered new in France with manual transmission without AC. The electrical harness is original. The FIP is type R25 without solenoid
Like Pawell66, I have 3 relays close to the left fender (cf photo) but one of them is different.
You can see right to left on the picture wiper relay, relay for csv on the middle and the third.
The third is a Bosch relay ref 0332 200 009 with 5 flat pins. The electrical connections on the pins are screwed.
pin 85 : wire brawn  pin 86 : wire yellow /grey
pin 30/51 : wire white/violet
pin 87: wire yellow  pin 87a: wire white
The relay receives no current at pin 30.
I see no correspondence with the electricalscheme 280sl august 70 but on the wiring diagram of model 280se we can see a relay with 5 pins for optional extra air conditioning (36) but there is not wire to the 87 pin.
Do you have some idea?
viard

Dear Viard

I have an idea of the functionality of that third screwed terminals relay (5 terminals).

Of course as your harness is old and time erases everything, your color description of each cable is not accurate.

This is what you indicated, and here after what I think it should be:

Terminal 85 (control pin) = Brown (ground all the time). Correct
Terminal 86 (control pin) =  Yellow / grey.  NO suggestion on this
Terminal 30/51 (feed) =. White/violet.  NO, it should be WHITE / YELLOW, and is the Headlight feed wire
Terminal 87 (output position 1) = Yellow (correct). This is the LOW BEAM output for headlights
Terminal 87a (output position 2) = White (correct). This is the HIGH BEAM output for headlights

So my opinion after thinking the issue some time, is that this is a kind of two position output relay for the headlights or something related to them.

Normally the HIGH BEAM/LOW BEAM headlight switching is made by the muli-function steering wheel switch assembly on W113.  On W111 that is done via a foot operated switch if your car is prior to 1967.

It may be the case that you have an originally installed accessory that uses the headlight signal for some purpose.

The first thing to do to confirm my hypothesis, will be to check if cable attached to terminal 30 is hot when you turn on the headlights via the main light switch at the dashboard.

Then if that is true go forward to look what is not connected near headlights at front of the car.

Remember that on a standard W113, each headlight is fed through the main fuse box on circuits 9/10 and 11/12.

Best regards
Eng. Leonardo Peterssen
Www.wiredoktor.com
Visit my website

[BobH]

One of these two relays operates CSV, the other one the mixture control solenoid on the fuel injection pump (I can never remember which is which, I think the one closer to the wiper relay is the one that operates solenoid on FIP, not sure). I assume you have 280SL where these relays are wired together, if you look underneath at the harnesses you will see they are connected.

They get signal from the wire that goes to starter, so they work when you crank the engine only. The other part of signal comes from the Thermo Time Switch. One relay switches on the CSV, the other one switches on the solenoid on FIP. They supply power (+) to both components. It is clearly shown on the coloured wiring diagram we have in our Technical Manual (components 20 and 21, CSV is 31 and FIP solenoid is 33).

I was writing above that, since my car is an Euro car, I do not have the mixture control solenoid on FIP, so the wire from the relay controlling this solenoid is just not connected.

I've never really studied the 280SL wiring diagram, i'm not sure if the schematic in the tech manual applies to all 280's or just later 1970 cars, but what i didn't realise is that the TTS only switches relay 20, to operate the intake starting valve (the CSV).  The other starting aid relay, number 21 is energised directly from the ignition switch and operates the FIP mixture control for as long as the engine is cranking.  Please correct me if i'm mistaken

In that case the mixture control has no timed signal, and it's not dependent on the temperature of the engine/coolant, so is there something on the actual FIP that dictates the length of time the mixture control activates, if not, what stops the engine flooding?

[Pawel66]

I've never really studied the 280SL wiring diagram, i'm not sure if the schematic in the tech manual applies to all 280's or just later 1970 cars, but what i didn't realise is that the TTS only switches relay 20, to operate the intake starting valve (the CSV).  The other starting aid relay, number 21 is energised directly from the ignition switch and operates the FIP mixture control for as long as the engine is cranking.  Please correct me if i'm mistaken

In that case the mixture control has no timed signal, and it's not dependent on the temperature of the engine/coolant, so is there something on the actual FIP that dictates the length of time the mixture control activates, if not, what stops the engine flooding?

My car is euro March 1970, the diagram in essence corresponds with what I have there, other than absence of the FIP solenoid in this case. I think the diagram description talks about "Status August 1970".

Yes, it is how it works - TTS is activating relay 20 and CSV (TTS provides gound). Relay 21, activating FIP solenoid, is always working when cranking, ground is permanent.

I am not sure what is the solenoid role in all this, I thought it was additional mixture enrichment for starting. I think I have read it is for the US version, Euro  versions did not have it, my car does not have it.

[Pawel66]

Dear Viard

I have an idea of the functionality of that third screwed terminals relay (5 terminals).

Of course as your harness is old and time erases everything, your color description of each cable is not accurate.

The 5 pin relays were commonly used in the era by other brands for headlights, as lpetersen described. Mercedes did not use them, at least not in our cars. Flat pin with screw in connection suggests fairly early type of this Bosch relay.

Maybe someone wired headlights through this relay or wired some other accessory.

Is it a French car? I remember that some accessories were required by law in France or at least were popular, e.g. battery shut off switch. Maybe it is something of this sort?