View Full Version : Question on Relays


Rollin
02/11/09, 06:43 PM
I was over at fordfuelinjection checking out the wiring diagram and I only see two relays in the system. 91-93 Mass air T Bird and 94-95 mass air mustang.

From what I have seen and read people say there are four relays in the system, my T Bird harness has two and I know a 3rd would be for a fuel pump but what is the fourth I am missing .

1. Relay is for Maf and Hego sensors
2. Relay for EFi or ECC
3. Fuel pump
4. ?

I hope the question makes since. My harness is out of a 93 T Bird
Mark

fordtrucks4ever
02/11/09, 09:54 PM
On the conversion 4 relays are used. The later model vehicles have an ignition switch with more than one set of contacts that are used instead of using relays. Bronco ignition switch has one contact for run and would be overloaded to route all of the efi wires thru it. If you have A/C installed another relay is used for WOT cutout. Not needed but doesnt hurt to have. Then you might as well rewire your headlights thru a relay too. Thats one more to add. If you find a later model Explorer with all relays and fuses together under the cover in one box will set you up for a great conversion. Able to hold 6 relays and all of the fusable links and general fuses you would need for upgrading the whole system. My current conversion is eliminating most of the load from existing fuse block. Stock fuse box will now just be used for dash and interior lights. Everything else goes thru new distribution box.

rjlougee
02/12/09, 12:25 AM
WOT Relay, basically cuts off the A/C compressor clutch when you go beyond 70% or so throttle, thus reducing parasitic loss so you accelerate faster.
Joe

Rollin
02/12/09, 06:20 AM
Are most relays the same, this Tbird has a couple relays still on the car that I can use for the fuel pump and the key switch. One relay is in the trunk which I assume is for the fuel pump because its right next to the safety fuel switch. The other is in engine bay but I'm not sure whats it hooked up to. If not were do I buy new relays.
Mark

ransil
02/12/09, 10:57 AM
Are most relays the same, this Tbird has a couple relays still on the car that I can use for the fuel pump and the key switch. One relay is in the trunk which I assume is for the fuel pump because its right next to the safety fuel switch. The other is in engine bay but I'm not sure whats it hooked up to. If not were do I buy new relays.
Mark


The EEC relay is different, its has different configuration that most standard relays.
I usually replace them with standard relays, I get all my relays from Fords in the junk yard.

rjlougee
02/12/09, 11:07 AM
Are most relays the same? Mark

Sort of, but not exactly. All the ones of the same color are the same, I. e. the green ones are all the same, the brown ones, the gray ones, etc... The major differences are in their function and they're designed to plug in differently because of it.
Joe

Rollin
02/12/09, 04:32 PM
So theoretically I should be able to cut the black ones out of the Tbird and wire them up for my fuel pump and key switch. Do I have to look for a certain amp or watts on them.

fordtrucks4ever
02/13/09, 12:39 AM
The internal configurations are different on some of the relays used. Earlier models have a specific purpose on a lot used. Some have internal diodes. Some only have enough terminals for the number of wires used. Later models can be replaced with the standard generic Bosch. These have 5 terminals that are all the same size. Earlier model Ford uses 2 small terminals to trigger the coil and have up to 3 larger for power/load with a choice of N/O or N/C positions. Some of the newer small square black ones that unplug from inside a distribution box are like the generic Bosch. The longer rectangular ones that are different colors are all specific purpose. Even tho there may be some the same color, an indexing key will be the difference. I have some black brown green and grey that have different key locations and not interchangable. The later model years before changing to Bosch style are more universal, but you still need to check internal configuration to make sure they do what you need. Some may automatically go to ground when normally closed and some may only allow power to travel in one direction. IIRC there are about 10 different types of relays that look the same on Cougar/Tbird, and only a couple are directly interchangable.

One of my conversions is from a Tbird. I have the EVTM for vehicle. If you have any questions, let me know and will try to help.

fordtrucks4ever
02/13/09, 03:06 AM
So theoretically I should be able to cut the black ones out of the Tbird and wire them up for my fuel pump and key switch. Do I have to look for a certain amp or watts on them.

If you unplug the connector and check to make sure they have all 5 terminals, then you might get lucky. I know the soft ride, hard ride, lcd illumination, and hyd motor relays all have diodes. A factory Ford WOT relay may only have terminals for normally closed. So those are a no go. Non OEM replacement relays may be more generic and have all 5 terminals usable. They will be recognized by not having the Ford logo on top, and one large rectangular opening for any color connector to plug in with out indents or slots for key. Depending on manufacturer the part # might be 913157 for black and 413157 for gray. I would get the fuel pump relay and inertia switch from the left side trunk with pigtails off donor car. At least there wont be any question with that.

For one conversion I ended up grabbing a small box with 4 seperate relays that slide out from an Aerostar. It was located on the drivers side against inner fender under master cylinder. So all of the relays will be in one location. They had all been replaced with non OEM, so I could make use of them for everything I needed.

The anti-lock power, FPR, and WOT relays will work for any of the 4 IF all 5 terminals are available. Your EEC and horn relay are located inside the distribution box. The ALP and WOT, are gray and located on passanger side up on firewall. If they have all 5 terminals, then will work. They can be swapped with non OEM replacements that are black. Horn relay feeds power internally to trigger coil, so it wont work for any you need.

If you use the Tbird distribution box, it already fuses the EEC and horn. It also has fused power that can be used for the other relays you need.

fordtrucks4ever
02/13/09, 03:20 AM
From what I have seen and read people say there are four relays in the system, my T Bird harness has two and I know a 3rd would be for a fuel pump but what is the fourth I am missing .

1. Relay is for Maf and Hego sensors
2. Relay for EFi or ECC
3. Fuel pump
4. ?

I hope the question makes since. My harness is out of a 93 T Bird
Mark

You will add relays for the HEGO and Igniton per the Mustang diagram on FFI. I think these are routed directly thru ignition switch on donor car. With exception for pinout locations on EEC module, the stock Tbird loom is basically same as the generic Mustang. Just may not have wires routed direct as the schematic appears.

Rollin
02/13/09, 04:28 PM
Thanks for the info guys, just when I thought this might not be to bad using my harness and adding relays to system, now I am wondering but shoot it cant be that hard. Anyway thank you for the help.
Mark

fordtrucks4ever
02/13/09, 07:52 PM
Its really easy. Once you have cut out the wrong wires a few times, then realize soldering isnt easy as your first thoughts of, melting a few wires that get crossed, or wonder why the factory loom has one wire spliced in about 12 places running in a complete loop that serves no purpose....just when you understand why, the tan/green wire changes colors four times before routing back to its starting destination and then realizing its not even being used but wont run without being there, causing the starter to stay cranking even when battery is disconnected while the headlights are flashing with horn blaring with sparks flying off the antenna causing carbon tracks to form across the windshiled, it starts to make some sense. Oh, and whats that humming comming from the gas tank, I have the keys in my pocket???? Wait, the gas tank is over there on the floor, where that smoke from????? And its all because that one relay had a voltage invertor that you were not aware of.....

Rollin
02/13/09, 07:56 PM
Its really easy. Once you have cut out the wrong wires a few times, then realize soldering isnt easy as your first thoughts of, melting a few wires that get crossed, or wonder why the factory loom has one wire spliced in about 12 places running in a complete loop that serves no purpose....just when you understand why, the tan/green wire changes colors four times before routing back to its starting destination and then realizing its not even being used but wont run without being there, causing the starter to stay cranking even when battery is disconnected while the headlights are flashing with horn blaring with sparks flying off the antenna causing carbon tracks to form across the windshiled, it starts to make some sense. Oh, and whats that humming comming from the gas tank, I have the keys in my pocket???? Wait, the gas tank is over there on the floor, where that smoke from?????

That just made me me spit my rum n coke all over the pc---that is to funny.
Im glad you took it so well.

Rollin
02/15/09, 05:52 PM
OK, after tearing my whole wiring harness apart and tracing the wires back down to were the EEC plugs in and checking the wiring diagram from my donor car, the harness only has two relays in the system.
ECC--relay
fuel pump --relay
there isn't a MA/02 relay or a Ignition relay unless its under the dash
My question is can I get away with only having two relays or do I try and
rewire it so there are four.
In the car wiring diagram for the oxygen sensors it does show a wire coming off both oxygen sensors and going to-- it only says Hot in Run Or Start Hego 10A not sure what that means.
donor car is a 93 T Bird
Any input would be great
Mark

lonesouth
12/29/10, 01:03 PM
any answers to the last question?

This only shows the EEC and Fuel pump relays

http://i1010.photobucket.com/albums/af224/lonesouth/Random%20Bronco%20Stuff/50harnessschem.gif

ransil
12/29/10, 01:55 PM
OK, after tearing my whole wiring harness apart and tracing the wires back down to were the EEC plugs in and checking the wiring diagram from my donor car, the harness only has two relays in the system.
ECC--relay
fuel pump --relay
there isn't a MA/02 relay or a Ignition relay unless its under the dash
My question is can I get away with only having two relays or do I try and
rewire it so there are four.
In the car wiring diagram for the oxygen sensors it does show a wire coming off both oxygen sensors and going to-- it only says Hot in Run Or Start Hego 10A not sure what that means.
donor car is a 93 T Bird
Any input would be great
Mark

You are correct there are only 2 relays ( 3 if you count the WOT relay).

normally when a harness get reworked to fit a Bronco the stock type relays are swapped out to Bosch style relays and moved to a convenient place to keep them all together.
Inside the harness you will find fuse links for the HEGO and Ignition I remove these and replaces them with a relay feed off a fuse.


The fuel pump relay will be controlled by the computer, the ground pin on the relay (85 or 86) will go to the EEC.

The other relays will be controlled by the key ( ign run).

Steve83
12/29/10, 06:56 PM
any answers to the last question?There's no "?" in the post above yours, and it's confusing. If you post your question worded your own way, I'm sure someone can answer it.

lonesouth
12/29/10, 07:56 PM
Specifically, what are the 4 circuits that the 4 relays control in the RJM and Kolibar reworked harness?

Steve83
12/30/10, 01:51 AM
1) EEC PWR
2) Fuel Pump
3) WOT A/C cutout
4) EEC pwr during cranking

ransil
12/30/10, 04:38 AM
1) EEC PWR
2) Fuel Pump
3) WOT A/C cutout
4) EEC pwr during cranking


It is not like this in the RJM , don't know what Kolibar does.

http://fordfuelinjection.com/index.php?p=6

the way I do mine:

Fuel pump
EEC power ( run)
HEGO
AC compressor ( onboard air)