• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech

Need help w/ wiring for electric water pump

  • Thread starter Thread starter gmkillr
  • Start date Start date Jul 2, 2006

gmkillr

Founding Member
Jul 13, 2002
606
1
18
Jul 2, 2006
#1
  • Jul 2, 2006
  • #1
I'll be the 1st. to tell you that I suck at anything electrical, and I need some help w/ the wiring for my relay & meziere electric water pump. This is what the schematics from meziere's site says-

O.K. there's 2 wires coming off of the pump-
1. blue wire=wire to a switched source
2. black wire=ground

There are 4 wires on the relay
1. blue wire= wire to a switched source
2. black wire= ground
3. orange wire= directly to alternator
4. green wire= fuel pump on signal

1st. question- For the green wire thats suppose to go to the "fuel pump on signal" , does that mean the fuel pump relay?, isnt it suppose to be 0 voltage w/ the key off and get 12 volts w/ the key in the on postion, correct? Thats how I wired it up, to the fuel pump relay and it has 0 volts w/ the key "off" and 12+ volts w/ the key in the "on" position Or is this suppose to be wired to somewhere else?

2nd. question- For the orange wire, do you really put it directly to the alternator? Thats just the same as just putting it directly to the battery, since the alternator runs directly to the battery. either way thats what I did.

3rd. question- For the blue wire, the wiring schematic says to wire both blue wires to a switched source, does that mean to a source that has 12 volts w/ the key in the "on " position only? Or does that mean to wire both of them to an actual switch that you flip yourself?

When I wire it all up like like mentioned above, & just put the 2 blue wires together and not wired to anything else the fuel pump turns on w/ the key in the "on" position and never shuts off, so I shut it off after I realized that the fuel pump wasnt shutting off. I want to wire this all up so the water pump runs just like normal w/ the car running or even w/ the key in the "on" position, and I also want it to work on a switch so I can just flip it w/ the car off and let the pump circulate the coolant. I messed w/ this for quite a few hours today and could not get anything to work like it should. Somebody please shed some light on this for me as im about at the end of my wick! :wallbash: :wallbash: :wallbash: Am I trying to do this all wrong or what? Please help me! :laugh:
 

gmkillr

Founding Member
Jul 13, 2002
606
1
18
Jul 3, 2006
#2
  • Jul 3, 2006
  • #2
Thanks for the help guys!
I'm pretty sure I got it figured out.
 

urban96

bubb rubb says:"woo woooooo"
Founding Member
Sep 24, 2002
3,464
1
69
Syracuse, NY
Jul 3, 2006
#3
  • Jul 3, 2006
  • #3
1) it should be fine hooked up to any switched 12V source (power only when key is on or your water pump will run all the time)

2) ground, simple.

3)i would think it goes to the battery and not the alt. i havnt heard of something running directly from that.

4)try wiring it up to a switch thats also connected to a constant 12V i think that might give you the option to switch it on when the car is off
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
31,179
34
129
Jul 3, 2006
#4
  • Jul 3, 2006
  • #4
I havent done one of these, but I'm decent at tracing circuits. On your relay, I dont even see where it sends power to the water pump. Is there a typo there?

It looks like the blue wire's hook-up is unnecessary and might be needing to go to the pump (does it have a number or nomenclature attached it it? Is it called the Normally Open terminal or terminal 87?).

I dont see how the pump gets power from the relay otherwise.

They probably recommend using the alternator for power because you can tap it at the power cable stud on the back of the alt (real close to your water pump). Connecting at the battery should be just fine, as was said.

Because of hte way you want it to function, you will be changing the control side hook ups anyhow (not using the fuel pump trigger, for instance).

Does it have some sort of thermostat or does it run at all times?

And before you go super far, if you want an awesome set-up and have the ching, check out the units at www.dccontrol.com.
(under fan control, you'll see where you can run the cooling fan and/or water pump). How great is it having them both in synch. And the fan controls are awesome (I run one on the '94)!

Otherwise, post more info and we can get you wired up how you want it (which will be simpler).

You're going to likely end up with the water pump blue wire attaching to the NO terminal on the relay. Then the relay will have a 12 volt and ground control side and the battery hook-up you already made. You're almost there.

Good luck.
 

urban96

bubb rubb says:"woo woooooo"
Founding Member
Sep 24, 2002
3,464
1
69
Syracuse, NY
Jul 3, 2006
#5
  • Jul 3, 2006
  • #5
yeah you bring up a good point, i didnt even notice that he didnt mention there was no wire going to the pump
 

mo_dingo

20+ Year Stangneter
Aug 26, 2003
3,031
2
58
Tucson, AZ
Jul 3, 2006
#6
  • Jul 3, 2006
  • #6
I think they chose the alternator as a 12V+ hot source b/c it's the closest 12V source and it's a pretty thick gauge.
 
You must log in or register to reply here.

Similar threads

3
Electric water pump wiring
  • 387lx
  • Feb 10, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
1
Views
198
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Feb 11, 2026
90trunk
C
Electrical HELP! 1989 5.0 Stick, Voltage Bleed onto Ignition Trigger wire
  • ChickenDeluxe
  • May 14, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
222
Fox 5.0 Mustang Tech May 24, 2026
ChickenDeluxe
C
1999 Mustang GT - No Start- Need help understanding the fuel pump circuit and how it works
  • 99gtGuy
  • Nov 4, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
1
Views
518
1996 - 2004 SN95 Mustang -General/Talk- Nov 7, 2025
04newedge-
0
Engine Fuel not pumping
  • Creomod
  • Apr 13, 2026
  • Fox 5.0 Mustang Tech
  • 2 3
Replies
46
Views
871
Fox 5.0 Mustang Tech Yesterday at 8:48 AM
AeroCoupe
W
Engine My engine dies after running 10 to 15 minutes under high heat.
  • Wylieone
  • Jun 21, 2026
  • Fox 5.0 Mustang Tech
Replies
7
Views
174
Fox 5.0 Mustang Tech Jun 22, 2026
Mustang5L5
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 1994 - 1995 Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?