1995 Ford Mustang 3.8L V6 - Electrical Issues - Need Help!

skimbap

Member
Jul 13, 2020
15
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California
Recently bought a 1995 Ford Mustang 3.8L V6 as a project car for $300. Didn't start or run, and it had been sitting in a garage for 4-5 years. It needs a lot of love.

The previous owner said it stalled while driving one day and he never looked into the problem. I'm a beginner and excited to work on this car!

What I've done so far (all before trying to start the car):
- Change the oil
- Replaced the battery and one terminal that was heavily corroded (it broke off when I was removing the old battery)
- Drained the gas tank and filled it up with new fuel
- Checked the coolant (it was still good) and topped it off
- Checked and adjusted spark plug gaps and used fogging oil to lubricate the cylinders before attempting to start the car (the spark plugs are pretty difficult to access on the 3.8L V6, so this took a lot of time)

After all that, I tried starting the car. The engine turns, but the car won't actually run.

Here's what I've checked so far:
- When I turn the key to the On position, I don't hear the fuel pump priming
- I checked the fuel pump fuse and it was good
- I also went ahead and checked all the fuses in the power distribution box
- Inertia switch is pushed down

Here's the electrical system schematic from the Haynes repair manual:
View: https://imgur.com/2mLtlEC

And here's the diagram of the fuse panel from the owner's manual:
View: https://imgur.com/EeQmTFa

So I tried checking the voltage with the key in the on position, and I tried checking it immediately after turning the key as well. Either way, there was no voltage in the fuel pump slot. I also checked all the other fuses, these are the approximate voltage results I got (in the same order from the second picture I linked above)

Ign. Sw. ~0.42
Ign. Sw. ~12.2
Ign. Sw. ~0.08
Hd. Lps ~11
EEC ~12.2
Htd. Bl. 0
Fuel Pump 0
Fan 0

I appreciate any help I can get! As a beginner, I know I might just be doing something dumb and/or missing something obvious, but let me know anyway! And I apologize in advance for any terminology that I'm not familiar with - I'll probably ask for a lot of clarification.

Thank you!

Update 7/16/20:
- I've been using these wiring diagrams to figure out the issue:
View: https://imgur.com/a/If7Vlxb

- Checked CCRM harness connector and only the pins circled in red got voltage:
View: https://imgur.com/a/XrFYpEj


Someone from reddit has also been helping me and they helped me deduce this so far:
- The line that links EEC and fuel pump fuses right before power enters the individual fuses.
View: https://imgur.com/a/XMYF3XV

- Since I had power at the EEC fuse but not at fuel pump fuse, either a jumper has failed inside the fuse box, or maybe one of the crimps that the fuel pump fuse plugs into may be the problem. Might want to grab a flashlight and inspect the slots that the fuse plugs into. - Checked fuse box terminals/slots and they all looked good
- (+) power should bridge from the same feed or fusible link that supplies power to the EEC fuse back to the battery
- Ground issue would not be the problem here, need to figure out why the fuel pump fuse has no (+) connection back to the battery
- Suggested a jumper with a fuse back to the battery in place of the fuel pump fuse or one connected to the line side of the EEC fuse will get the pump operating again as a test.
- Sounds like one or more of the fusible links that bring power to the fuse box from the battery may have blown. Can anyone help me locate this? The reddit user said for older models it might be at the battery side post of the starter solenoid

(here's the thread: View: https://www.reddit.com/r/MechanicAdvice/comments/hq6hwq/1995_ford_mustang_38l_v6_fuse_box_problem/fy1w2t3/
)
 
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Chythar

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There's two places I'd suggest to check. The fuel pump relay is inside the CCRM in the engine bay (it's the black box on the metal bracket next to the coolant overflow tank). The relay is not user replaceable, you'll have to swap the whole CCRM. The second is the inertia switch in the trunk, on the driver's side near the tail light. There's a hole in the trunk liner to get to the switch. The inertia switch cuts off the fuel pump in case of an accident. With the switch tripped, the car will do exactly what you're experiencing - car turns over but won't start. The inertia switch is a button - if you can push it down, it should click in place.

Now, I've never heard of an inertia switch failing before but it's an easy thing to check. As for the CCRM, I don't have a wiring diagram handy but I imagine you can check the voltage in and out on its wiring harness.
 

skimbap

Member
Jul 13, 2020
15
2
13
26
California
There's two places I'd suggest to check. The fuel pump relay is inside the CCRM in the engine bay (it's the black box on the metal bracket next to the coolant overflow tank). The relay is not user replaceable, you'll have to swap the whole CCRM. The second is the inertia switch in the trunk, on the driver's side near the tail light. There's a hole in the trunk liner to get to the switch. The inertia switch cuts off the fuel pump in case of an accident. With the switch tripped, the car will do exactly what you're experiencing - car turns over but won't start. The inertia switch is a button - if you can push it down, it should click in place.

Now, I've never heard of an inertia switch failing before but it's an easy thing to check. As for the CCRM, I don't have a wiring diagram handy but I imagine you can check the voltage in and out on its wiring harness.
Thank you for your response!

I did already check the inertia switch and it was pressed down. I even tried hitting the switch to test it out, and the button popped up and I pushed it back in.

So I think you may be right about having to replace the CCRM. Another sign that I think you're right is that this site (https://easyautodiagnostics.com/ford/3.8L/ccrm-module-mustang-1) says the CCRM also controls the AC compressor, and I noticed that the AC wasn't working either when I tested it.

Looks like I'll have to find a replacement!

UPDATE:
I have a separate thread regarding this issue on Reddit - I changed my mind on just replacing the CCRM since I want to make sure it's not another issue before I just buy a replacement part that won't actually fix the issue.

Here's the thread on Reddit:
View: https://www.reddit.com/r/MechanicAdvice/comments/hq6hwq/1995_ford_mustang_38l_v6_fuse_box_problem/fy1w2t3/


Not really sure how to move forward, mostly due to my inexperience with electrical systems and testing them. Do you have any suggestions?
 
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rayhodge

New Member
Sep 15, 2020
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Hi, I also have a 95 3.8 that stalled. I have had a mixed bag of issues. Originally thought that it was a fuel pump issue so after some test I replaced fuel pump which did not fix my problem. Begin digging into the CRM and got the car rack and crank it up at times and it would run fine and then others it won’t do anything but turnover unless I push the pedal. and then it will start and only stay running if I hold the throttle pedal open. I’ve tried multiple times to get codes to come up and with no luck. There are times it seems like it’s an electrical issue may be a loose connection or something just curious to if you found a solution to yours?
 

rayhodge

New Member
Sep 15, 2020
4
0
1
52
Clover, SC
Hi, I also have a 95 3.8 that stalled. I have had a mixed bag of issues. Originally thought that it was a fuel pump issue so after some test I replaced fuel pump which did not fix my problem. Begin digging into the CRM and got the car rack and crank it up at times and it would run fine and then others it won’t do anything but turnover unless I push the pedal. and then it will start and only stay running if I hold the throttle pedal open. I’ve tried multiple times to get codes to come up and with no luck. There are times it seems like it’s an electrical issue may be a loose connection or something just curious to if you found a solution to yours?
Also, the cooling fan stays on constantly, not sure how long that’s been going on
 

skimbap

Member
Jul 13, 2020
15
2
13
26
California
Hi, I also have a 95 3.8 that stalled. I have had a mixed bag of issues. Originally thought that it was a fuel pump issue so after some test I replaced fuel pump which did not fix my problem. Begin digging into the CRM and got the car rack and crank it up at times and it would run fine and then others it won’t do anything but turnover unless I push the pedal. and then it will start and only stay running if I hold the throttle pedal open. I’ve tried multiple times to get codes to come up and with no luck. There are times it seems like it’s an electrical issue may be a loose connection or something just curious to if you found a solution to yours?

Unfortunately, I still haven't found a solution.Someone on another mustang forum tried to help me out and diagnosed that it was a bad CCRM - I replaced it and that didn't work out. After some more digging and realizing I couldn't figure it out, I had a mechanic come and check it out. He diagnosed that it might be a bad PCM since it wasn't receiving ground from the PCM to command fuel pump on. He checked power and grounds to the PCM and they were good. I just tried my PCM replacement and no luck.....

At this point, I'm at a total loss.
 

rayhodge

New Member
Sep 15, 2020
4
0
1
52
Clover, SC
Unfortunately, I still haven't found a solution.Someone on another mustang forum tried to help me out and diagnosed that it was a bad CCRM - I replaced it and that didn't work out. After some more digging and realizing I couldn't figure it out, I had a mechanic come and check it out. He diagnosed that it might be a bad PCM since it wasn't receiving ground from the PCM to command fuel pump on. He checked power and grounds to the PCM and they were good. I just tried my PCM replacement and no luck.....

At this point, I'm at a total loss.
Dang, ok thanks for the reply. Good luck
 

rayhodge

New Member
Sep 15, 2020
4
0
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52
Clover, SC
Dang, ok thanks for the reply. Good luck
So, I went to the local junk yard and picked up a used PCM/ put it in and now the car seems to be doing good with the exception that the cooling fan still runs on high with the key on, it does shut off with the car.