Transposing Relay Wiring

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

1987 GMC Jimmy

Automobile Hoarder
Joined
Jan 23, 2016
Posts
5,848
Reaction score
2,387
Location
Mississippi
First Name
Jesse
Truck Year
1987
Truck Model
V1500 Jimmy
Engine Size
350
I’ve had a months long electrical gremlin with the wires that go to the relay that controls my dashpot/idle up solenoid/fast idle solenoid, and something’s shorting out and blowing my ECM-I fuse. I did a “field dressing” when I was away from home that actually lasted a few months. When it happened again, I fixed it correctly, and it lasted about a day. I figured I’d just get a universal relay and pigtail and be done with it, but I’m having trouble with the coil portion of the diagram (pins 85 and 86). Any thoughts? If I had a wiring diagram for this, I’d be set, but unfortunately I couldn’t find one anywhere. 3 and 4 are getting twelve volts, but I thought I was supposed to be getting twelve to five, and there was negligible voltage there. I also thought one side of the coil was supposed to go to ground.

1=87
2=87a
3=?
4=?
5=30

You must be registered for see images attach
You must be registered for see images attach
 

gmachinz

Harnessworx Inc
Joined
Nov 10, 2012
Posts
762
Reaction score
287
Location
Iowa
First Name
Jabin
Truck Year
1986
Truck Model
K10
Engine Size
350
Yes 3 and 4 would be a 12V input trigger and a ground. Unless there is a diode it wont matter which is which on the generic relay-not so sure on the GM relay tho-I’d have to check my illustrations.
 

1987 GMC Jimmy

Automobile Hoarder
Joined
Jan 23, 2016
Posts
5,848
Reaction score
2,387
Location
Mississippi
First Name
Jesse
Truck Year
1987
Truck Model
V1500 Jimmy
Engine Size
350
Crap. Then something’s wrong or the diagram’s wrong. Could damage in the original connector cause the voltage to jump over one? And I thought the pin giving me less than a volt should be a 12V constant as well. I can make sure the fuse didn’t blow again, but I was getting power to the ECM while testing so it shouldn’t have.
 

1987 GMC Jimmy

Automobile Hoarder
Joined
Jan 23, 2016
Posts
5,848
Reaction score
2,387
Location
Mississippi
First Name
Jesse
Truck Year
1987
Truck Model
V1500 Jimmy
Engine Size
350
Went ahead and wired it as best I could, the dashpot works again, and there’s no ECM-I fuse short (for now). OEM relay number is 14078915, aftermarket connector is S615. GM used this relay on various cars and trucks throughout the 1980s for the air injection, fuel pump, and/or controlling the carburetor dashpot as in my case. I saved some money going the universal route, and I’ll attach my work below.

You must be registered for see images attach
 

Backfoot100

Full Access Member
Joined
Aug 18, 2017
Posts
374
Reaction score
643
Location
Florida
First Name
Eddie
Truck Year
1986
Truck Model
C1500 Suburban
Engine Size
Carbed 350
According to DIN standards 85 is ground and 86 is 12V.
Should be easy to ohm out from the relay to the connector to determine which is which on the connector.
 

73c20jim

Full Access Member
Joined
Jun 11, 2018
Posts
2,282
Reaction score
2,924
Location
Tombstone, AZ
First Name
Jim
Truck Year
1973, 1973
Truck Model
C20 2WD Custom Deluxe. C10 2WD Base Model
Engine Size
350 CID 195/260 HP Goodwrench crate, 400 CID 2bbl
1=87
2=87a
3=?
4=?
5=30

You must be registered for see images attach
You must be registered for see images attach

3 & 4 are the trigger wires as already said,

When the relay is at rest 5 & 2 are connected.

Trigger the relay and 5 & 1 are connected.
 

Latest posts

Forum statistics

Threads
41,857
Posts
903,627
Members
33,370
Latest member
mitchell1128
Top