Fuel ['95 3.8 v6] Fuel Pump Ground location ? Everything else is ok.

98Mustang2017

Active Member
May 3, 2017
150
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38
ct
#1
The CCRM still clicks.
Fuse is good.
i think the inertia switch in the trunk is ok. It is pushed down, although the CCRM still clicks when it is pulled up.

I took the fuel pump out of the gas tank, put a battery to the pump leads, and the pump runs.

Have looked in the obvious spots for grounds but didn't notice any for those 2 wires..
If i don't find them i may run an inline switch to the pump instead of tearing the car apart to find it.
 
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wmburns

SN Certified Technician
Aug 14, 2009
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#2
FWIIW, the CCRM is upstream of the trunk IFS switch. Therefore a bad IFS switch will not affect the IFS switch.

Suggest testing for key on power on BOTH sides of the IFS switch. If the IFS switch really is bad one would expect to find power on one side but not on the other. Best to use a test light on a known good ground.

Note, the V6 does not power the fuel pump all of the time that the key is on. It pulses (primes) and then the PCM turns off the fuel pump. To test power it will be necessary to cycle the ignition switch off/on.

IF there's no key on pulsed power on either side of the IFS switch, then the problem is upstream.

IF there's pulsed key on power on BOTH sides of the IFS switch, THEN the problem is down stream of the IFS switch.

Or disconnect the IFS switch and test through the IFS switch with a VOM. This method has the disadvantage that it will not "load" the circuit. Possible to have a high resistance connection that a simple Ohm test will not detect.

Also note that it is POSSIBLE to have a blown fuel pump fuse and the CCRM still clicks. Suggesting confirming power on both sides of the fuel pump fuse with a test light.

IF this were my car and I already had the tank down (or the wiring apart) to test the fuel pump directly, why not test the ground all the way back to battery negative? Use a test light with the pig tail on battery positive. Then you will know IF there is a ground problem or not.
 
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98Mustang2017

Active Member
May 3, 2017
150
12
38
ct
#3
The IFS switch does not have power on either side.
The fuel pump does not receive the pulsed power when the car clicks on either.

Are their two fuel pump relays? one in the CCRM and one above the ECU ?
 

wmburns

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Aug 14, 2009
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#4
With NO POWER at all ever at the IFS switch we need to go upstream.

I'm assuming that you have CONFIRMED power on both sides (in/out) of the battery junction box (BJB) fuel pump fuse.

At the CCRM confirm power at the CCRM #11(Y) wire. If no power THEN it's either a blown BJB fuel pump fuse or a wiring fault.

At the CCRM, put a test light on pin #24 (R) wire. Turn the ignition switch on and verify that the test light is bright.

At the CCCM, put a test light on pin #5(DG/Y). Cycle the ignition switch and the test light should pulse. If NOT then the CCRM is bad.
 

98Mustang2017

Active Member
May 3, 2017
150
12
38
ct
#5
With NO POWER at all ever at the IFS switch we need to go upstream.

I'm assuming that you have CONFIRMED power on both sides (in/out) of the battery junction box (BJB) fuel pump fuse. ---------------

At the CCRM confirm power at the CCRM #11(Y) wire. If no power THEN it's either a blown BJB fuel pump fuse or a wiring fault.------------

At the CCRM, put a test light on pin #24 (R) wire. Turn the ignition switch on and verify that the test light is bright. --------------

At the CCCM, put a test light on pin #5(DG/Y). Cycle the ignition switch and the test light should pulse. If NOT then the CCRM is bad---------.
I tested the wires with and without the CCRM plugged in and got the same results. I was able to use a MultiMeter though.

No power on Red #24
and
No cycled power on #5{DG/Y).

---------------------------------------------------------------
FOUND THE ISSUE!

For anyone that came across THIS wiring diagram for the '95 3.8 v6 mustang::
The HTD BL and Fuel Pump fuse is swapped around. That being said, after i tore apart my CCRM, dropped the tank, and etc. it turns out either the Diagram was wrong or previous owner swapped things around.

Final verdict: blown Fuel Pump fuse.
Swapped fuses and the Pump now works.

diagrrrrr.png


Anyways,
thank you wmburns for helping me.
I now know a little more about electrical and wiring and the CCRM.
 

wmburns

SN Certified Technician
Aug 14, 2009
4,895
348
154
Houston Texas
#6
The test light can be one of the electrical trouble shooter's best friend. A quick and easy test is to put the test light pig tail battery negative. Touch the probe to each side of the fuse. What you are looking for is any fuse with power on one side but not on the other. This gives an easy and fast way to test for a blown fuse.

Glad you got a fix.
 
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