Author Topic: Relay Experts around?  (Read 2146 times)

TEJOLX47

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Relay Experts around?
« on: March 02, 2020, 11:30:01 »
Hi everyone,
Is there an expert in Electrical components? Namely Relays?
Someone (I don’t know who) mounted two simple auto relays in sequence to energize my “Constant Speed Solenoid”.
I have a 1970 280SL with Emission Control System.
Here is a short description of the wires:
Relay 1:
•   Ground (30?)
•   Ignition (85?)
•   Transmission (pressure) solenoids (86?)
•   Jump to next Relay (87?)
Relay 2:
•   Battery (30?)
•   Ignition (85?)
•   Jump from previous Relay (86?)
•   Constant Speed Solenoid (87?)
My question is very simple: can I consolidate all this on a single relay? How?
I assume that the Automatic transmission solenoids are only powered when the ignition is on, so that would make the ignition wires redundant.
Many thanks.
Francisco

Note 1: The transmission solenoid wire feeds the Emission control system which, in turn, feed Relay 1.
Note 2: The activity of this Relay couple has been verified.
Francisco

1970 280 SL (US delivered, Auto, AC, PS)
181 Light beige with 423 Tobbaco brown top

Jonny B

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Re: Relay Experts around?
« Reply #1 on: March 02, 2020, 13:28:42 »
It would help to post a photo of what and where these relays are located. There are two in a black plastic shell that are mounted back to back just back (towards the driver) from the battery. There should also be a small ~4cm vacuum control valve in front of the outer black relay, this controls the advance.

Tyler S put my system back in order, but he meticulously followed the BBB on how this system operates to figure out what was working and what was not. He is the man for this!

PS even found that the internals of one of the black relays did not match the schematic that was on the outside of the box....the schematic was correct and the internals were from ???
Jonny B
1967 250 SL Auto, DB 568
1970 280 SL Auto, DB 904
1966 Morris Mini Minor

jeffc280sl

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Re: Relay Experts around?
« Reply #2 on: March 02, 2020, 14:23:22 »
Attached is a standard relay wiring diagram.  Its function is pretty straight forward.  I has 12V+ leg (pin 30),  12V+ switched input leg (pin 86), 12V- switched input leg (pin 85) and 12V+ output legs (87 and 87a)

The use of these devices in your car is the issue.  Your pin ids have ? marks for connectivity.

You need to verify relay pin (in and outputs) and then post a wiring diagram similar to the relay attached for your application. 

The wiring in your circuits does not follow standard relay wiring conventions. 

assuming your description is correct, I think you can accomplish the function desired in your two relay system with one relay.  Disconnect relay 1.
On relay 2 connect ignition input to pin 86.  On relay 2 connect the transmission pressure switch to pin 85.  Leave battery input pin 30 and CSS output on pin 87.
« Last Edit: March 02, 2020, 15:33:03 by jeffc280sl »

TEJOLX47

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Re: Relay Experts around?
« Reply #3 on: March 02, 2020, 15:35:52 »
Hi Jonny,

I think you mention the 4 components of the Emission Control System.
Those are in order and in place, i.e., just behind the battery.
The two relays I am taking about, are two plastic hella MB relays that were hidden just near washer bag (and the "other" relays).
Cheers
F
Francisco

1970 280 SL (US delivered, Auto, AC, PS)
181 Light beige with 423 Tobbaco brown top

TEJOLX47

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Re: Relay Experts around?
« Reply #4 on: March 02, 2020, 15:45:52 »
Hi Jeff,

That is in line with my thoughts.
When the transmission solenoid is activated (86) it closes the circuit coming from ignition (85) and activates the coil.
That, in turn, will connect battery (input, 30) to CSS (output, 87).
Apparently I have no need for ground, right?
I will try that.
Many thanks
Francisco
Francisco

1970 280 SL (US delivered, Auto, AC, PS)
181 Light beige with 423 Tobbaco brown top

jeffc280sl

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Re: Relay Experts around?
« Reply #5 on: March 02, 2020, 15:58:45 »
Ground in your setup is provided by the transmission pressure switch.  I suggest this ground input be terminated on pin 85.  The ignition input belongs on pin 86.

Here is the way it will work.  When the ignition system is on (pin 86) and the transmission provides a ground input on pin 85 power will be switched from pin 30 to the CSS on pin 87

TEJOLX47

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Re: Relay Experts around?
« Reply #6 on: March 03, 2020, 12:07:37 »
Many thanks!!
;) ;)
Francisco

1970 280 SL (US delivered, Auto, AC, PS)
181 Light beige with 423 Tobbaco brown top

jeffc280sl

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Re: Relay Experts around?
« Reply #7 on: March 06, 2020, 14:43:15 »
let us know how this implementation works out.  would be nice to do pros and cons on manual and automatic css solutions so that we can offer the best solution to members