1995 Mustang Gt Cranks But Will Not Start

[dredd0822]

Hi everyone, first post here. It's about the infamous "crank but will not start" problem.

I have a 1995 Mustang GT 5.0, that I bought back in May 2015.
This Mustang was 100% bone stock when I got it, about 90K miles.

As soon as I got it, I did the following upgrades, engine wise (many other upgrades, non-engine wise as well):
1. Tune up: New plugs, new Ford Racing wires, new coil, new distributor cap and rotor, new fuel filter.
2. Cold-air kit
3. Oil change

The car ran great up until a month and a half ago. I went out of town and left it parked in my driveway for a week.
When I got back, the car would crank, but this time would no longer start.

Since then, I have intalled the following parts, keeping in mind that I would have to install them anyways, since the car was completely original, 20 years old, and I figured these parts would fail sooner or later:
1. New battery
2. New PA Mini-starter
3. New BBK 255 lhp fuel pump
4. New fuel filler neck
5. New Summit Racing Billet Distributor - my mechanic friend verified it was installed correctly
6. TFI Module
7. Reman CCRM

After all these upgrades, the car is still in the same condition, cranks but won't start. A mechanic friend of mine came over to look at it, and determined that the fuel pump is not priming when I turn the key. He checked the fuses in the engine compartment, underneath the dash, and they all look good. He verified that the fuel trip switch is not activated. He then jumped a cable that connects to the fuel tank in the rear, and this time, he was able to get the car to start. It turned on and ran fine while the cable was jumped. So it appears that no power is being sent to the fuel pump when I turn the key. Is there anything else electrical wise that remains to be looked at, that I might've missed? Or is it a fuel problem? I've looked at the no-start checklist, but I must say I'm not very saavy with electronics, so I get a little lost in some of the instructions.

I've looked all over this forum, as well as in other forums, for this issue, but everything I replace still doesn't fix it.
I'm at the end of my rope, and we've had only one car for the last month and half, so this situation is getting stressful.

Any ideas on else it could be?

Thanks.

 

[jozsefsz]

Seems that your friend eliminated a fuel pump or pressure problem by jumping it -- possibly a wiring or connector issue somewhere along the way. You'll need to work your way backwards with a voltmeter and figure out where the power stops getting to the pump. It could be all the way back at the ECU, but probably not. Start at the inertia switch, it could be faulty even if not tripped.

 

[dredd0822]

Thanks for the advice.

Here's what I've done so far:

From the No Start Checklist, I took the EEC test connector in the engine compartment, and did the following:
"find the EEC test connector and jump the connector in the Upper RH corner to ground. The EEC connector is near the wiper motor and LH hood hinge."
Still, nothing happened. The fuel pump did not prime, and the car did not start. The checklist goes on to say that if the fuel pump primes, it means the relays and the inertia switch are ok. Since the fule pump did not start, and I already replaced the CCRM, I figured it might be the inertia switch.

So what I did was remove the connector from the inertia switch, then jumper both wires in the inertia switch connector. Still, nothing happened when I tried to start the car. It just cranked.

So it seems that absolutely no power is getting to either the inertia switch or the fuel pump, not even when I try trick the fuel pump into running. I don't remember exactly which wire it was that my friend jumped by the rear that caused the car to start.

Note: When I say jumping a cable above, I mean that I ran a wire with one end in one of the connectors, and the other end to the other connector. I hope that's how it's done.

Any ideas on what else it could be?

 

[jozsefsz]

You're really going to want a volt-meter (or a simple test light) to determine where power is and where it isn't. It sounds like you jumped around the inertia switch properly, but there could still be a break in the wire between the switch and the fuel pump. The only way to tell is to check if you have voltage at the switch connector.

Jumping at the test port has possibly eliminated the ecu as the culprit, but you don't really know since that's just grounding the ecu fuel pump test port (it assumes your + voltage circuit is intact and just turns on the relay within the ccrm - you should minimally have heard the relay make a soft click).

The + voltage comes via the ccrm. You'll want to probe what's coming out at the ccrm (if nothing you may have an ecu or ccrm problem, or within their wiring). If something, you have a break in the wiring beyond the ccrm towards the pump.

If you're lucky using jumpers can sometimes identify a simple electrical problem, but the definitive way is to check for voltage / continuity at each point along the way from the ecu all the way back to the pump. It sounds like your friend is ok with electrical systems, perhaps he can lend a hand?

It's not a very complicated system honestly. Below is the wiring diagram. Check if you have voltage coming out of the dark green / yellow wire at the ccrm first.
http://www.veryuseful.com/mustang/tech/engine/images/Mustang-94-95-CCRM-PCM-Transmission.gif

 

[jozsefsz]

This image has some more detailed information about the wiring before the ccrm (the wires / fuse-links coming from the battery and the signals coming from the ecu). Focus on the top left (Fuel Pump Relay).

The PINK & BLACK wire is voltage coming from the fuel pump fused wire (direct from the battery, hot at all times) to the CCRM. It should show 12v always. If it does not, you have a wiring, fuse, or fusible link problem between the battery and the CCRM.

The RED wire to the CCRM is voltage coming from the PCM power relay. It should show 12v when the ignition switch is on. If not, you have a wiring, fuse, or fusible link problem between the battery and the CCRM via the PCM power relay. It is doubtful there is a problem here because the car runs when the fuel pump is given 12v, which means the PCM is getting power.

The DARK GREEN / YELLOW wire from the CCRM should have 12v when the engine is priming or running. It should also have 12v when the data-link connector (test port) is grounded. It appears to feed into the PCM at pin 8, probably telling it the fuel pump should be running based on it receiving voltage at that pin.

The LIGHT BLUE / ORANGE wire from the PCM (pin 22) provides the ground to the fuel pump relay when it wants the fuel pump on (when priming or running). You've probably eliminated the problem here by grounding at the test port.

So... check for 12v at PINK & BLACK at the CCRM. Then, jump the test port to ground again, and check for 12V at the DARK GREEN / YELLOW wire from the CCRM.

If you do not have 12v at PINK & BLACK, figure out why (fuel pump fuse, fuse link in the PINK & BLACK wire, the wiring itself).

If you have 12v at PINK & BLACK, and no voltage at DARK GREEN / YELLOW with the test port jumped, your CCRM is bad (or the pinout is wrong for the car).

If you have 12v at PINK & BLACK, and 12v at DARK GREEN / YELLOW with the test port jumped, you have a problem somewhere between the CCRM and the fuel pump.

If you have 12v at PINK & BLACK, and 12v at DARK GREEN / YELLOW with the test port jumped, and you have no voltage at the INERTIA SWITCH, you have a problem somewhere between the CCRM and the INERTIA SWITCH.

If you have 12v at PINK & BLACK, and 12v at DARK GREEN / YELLOW with the test port jumped, and you have 12v at the INERTIA SWITCH, you have a problem somewhere between the INERTIA SWITCH and the fuel pump.

 

[dredd0822]

Thank you so much for this detailed info, jozsefsz.

My friend is coming over tonight, and we're gonna use the volt tester to go through this list step by step. I really hope it's not the CCRM, I just bought a reman one from RockAuto last week and installed it.

 

[jozsefsz]

Awesome let us know how it goes! Here's a CCRM pinout diagram too if it helps.

 

[dredd0822]

Ok, so we ran the tests that you outlined above, and this is what we found:

The pink/black wire is always hot. When I turn the key, the dark green/yellow wire does not have voltage.
When my friend jumped the dark green/yellow wire, then the car turned on.

So it appears that the fuel relay is not closing?

I also confirmed that the CCRM clicks when I try to start the car.

Could the CCRM be bad? I find it hard to believe, since it's a reman that I just purchased from Rock Auto. I also tried the original CCRM, and it's the same result.

 

[jozsefsz]

Interesting, so it clicks when you try to start (and should also when you jump the test-port to ground) but you're not getting voltage out of the fuel pump lead. Jumping voltage to that CCRM output lets the fuel pump / car run. You and your friend did a great job narrowing it down. This eliminates everything before the CCRM and everything beyond the CCRM.

It appears to me that the fuel relay is not closing, or that perhaps the CCRM harness at the dark green / yellow wire has a continuity problem. You're right it's unlikely that two CCRM's (one reman) would have the same problem, so I'd focus on the harness connector. Remove it and check the condition of the pin on the back-side of the connector, and check resistance between the pin & back-probing of that lead. If you can pull the dark green / yellow lead out of the harness (looks like pin 5) and probe the CCRM output directly (with the test port jumped) then you can eliminate a harness problem.

The only other even remote possibility is that the CCRM isn't a 100% match to your pinout (different year / engine combinations used a similar looking CCRM but the pins don't 100% match). You could jump the test lead to ground and go hunting for 12V on each of the CCRM output wires. Make a note of each one that has 12v coming out. The un-jump the test lead from ground, and see if there's a pin that is no longer putting out 12v. Then move the green & yellow wire to that output.

Let me know how that goes, and if it's still not running, and we can talk about wiring in an external relay to take the place of what's going on in the CCRM. $10 in parts and you'll never have to deal with the CCRM (for fuel) again.

 

[jozsefsz]

If you get it working by checking the harness, awesome. If not, here's how to wire in an external relay (figured I'd post this in advance since I had a few minutes).

Pick up a standard relay at your auto parts store (one that works for fog lamps is aok). They sometimes even include a pig-tail with wires, otherwise you'll want some crimp-on female blade connectors.

Connect the pink & black wire to port 30 on the relay below (remove it from the CCRM harness by cutting or de-pinning). It's already fused since it's the always-12V wire coming from the fuel pump fuse.

Connect the dark green & yellow wire to port 87 on the relay below (remove it from the CCRM harness by cutting or de-pinning).

Connect the light blue & orange wire to port 85 on the relay below (remove it from the CCRM harness by cutting or de-pinning)

(For any that you cut, do so a little away from the harness so you could re-connect & solder if you wanted to).

Connect a 12v ignition-switched source to port 86 on the relay below. (You could borrow that from pin 13 on the CCRM or any other fused location - don't cut or remove because it's needed to power the PCM relay).

(Note: it's probably not super important for this to be switched, you could probably get away with using the same pink & black wire (constant 12v) to feed port 86 as port 30, but to make it work exactly like the CCRM, use a switched source). A "tap-a-fuse" works well for this from a switched fuse like that for the radio.

You'll now have an external fuel pump relay that's easily replaceable and not have to worry about the CCRM again. It will also be just as reliable (if not more), and will work identically to factory (the fuel pump will prime and run when the computer tells it to).


There's also a simpler option if you don't feel like dealing with the relay. Just remove the dark green / yellow lead from the CCRM, and run a 12-v ignition-switched lead to it. (Tap-a-fuse will work well for this too). Make sure it's a fused lead, and note that the fuel pump will always run when the ignition is on. That's no biggie, just keep it in mind if you like to sit there running the radio with the engine off.

EDIT: Something's messed up with this attachment, clicking it gives an error, so hopefully you can squint. It's a standard automotive 4-lead relay.

 

[dredd0822]

So I looked at the CCRM that I bought from Rock Auto, and I think I bought the wrong one. Looking at the Alt OE Numbers of the one that I bought, they are:
Alternate/OEM Part Number(s): F4ZZ12B577A, F6SF12B577AB, F6SZ12B577AA, F6SZ12B577AB, F7CF12B577AA, F7CZ12B577AA, F7CZ12B577AB

When I search those OEM part numbers, I don't get results for a 95 Mustang GT.

I looked at my factory CCRM, and it's F48F12B577AA. RockAuto carries another CCRM that corresponds to that part number.

I think the one I bought is actually for V6 Mustangs, although it was listed as fitting a 95 Mustang GT 5.0
I remember reading in another thread that the CCRM for the V6 Mustangs will actually not work for the V8s. Is that true? Is it just the fuel pump circuit that doesn't work in this case?

Anywho, I'm going to Autozone today to get one that for sure corresponds to F48F12B577AA to see if that takes care of all this. Hopefully that's the extent of the issue.

 

[jozsefsz]

The v6 and v8 CCRM's are different, but it's usually the fan not working properly that folks notice from a same-year v6 CCRM. (I have seen posts of people doing 5.0 swaps into different years, 96 and up, where the fuel pump doesn't work -- so if the CCRM they sent you was intended for a later year v6, it could definitely be the problem).

So you'll definitely want to get the right one, and hopefully you're right and that's the extent of the issue. Even with a reman that is the correct part, you never know if you got a dud (RockAuto's good about returns though I think you eat the shipping -- I see the notes on that part and they've made ordering it confusing with multiple 'programming' options so hopefully they'll be cool about it and meet you half way on shipping). Good luck!

 

[dredd0822]

I'm going to go get the CCRM from Autozone later today.

However, I did have one more question. When my friend jumped the Dark Green/Yellow wire yesterday, that made the pump turn on and got the car started, he did it right where the wire goes into the CCRM connector.
From this, my guess is that the wiring from the CCRM to the Inertia Switch and Fuel Pump is fine, right?
It HAS to be the fuel pump relay inside the CCRM/or the CCRM as a whole, right?

Also, is there a special process when installing a new CCRM, aside from disconnecting the battery?

 

[jozsefsz]

I'm going to go get the CCRM from Autozone later today.

However, I did have one more question. When my friend jumped the Dark Green/Yellow wire yesterday, that made the pump turn on and got the car started, he did it right where the wire goes into the CCRM connector.
From this, my guess is that the wiring from the CCRM to the Inertia Switch and Fuel Pump is fine, right?
It HAS to be the fuel pump relay inside the CCRM/or the CCRM as a whole, right?

Also, is there a special process when installing a new CCRM, aside from disconnecting the battery?

You're absolutely correct. You have voltage on the pink wire, ground on light blue, the pcm works, and no voltage comes out of dark green. Jumping voltage to dark green lets you run. So the problem is right at the ccrm or its harness. Everything towards the pump and the pump itself must be fine.

 

[jozsefsz]

You're absolutely correct. You have voltage on the pink wire, ground on light blue, the pcm works, and no voltage comes out of dark green. Jumping voltage to dark green lets you run. So the problem is right at the ccrm or its harness. Everything towards the pump and the pump itself must be fine.

And no special process, disconnect battery and bolt it up.

 

[dredd0822]

OMG, I give up. So I replaced the CCRM again with the one from Autozone, and still nothing.
I don't know what else it could be. The wiring from dark green to the fuel pump must be good, since it turned on when we jumped it right from the CCRM connector.

Three CCRMs cannot be bad at the same time.

The car came with an aftermarket alarm system (Galaxy brand), but we've already tried to reset it, and that didn't do it either. Besides, it does try to start, we just can't get the fuel relay to activate.

I guess my last question is what supplies power to the dark green wire itself?
Because the last thing I can think of is that the reason the fuel relay doesn't activate is because there's no power coming from the dark green wire in the CCRM harness, so what supplies power to that wire?

Thanks for the suggestion for a workaround to this problem, but I'm a systems analyst who debugs software defects for a living, so this kind of "bug" really bothers me, and my brain won't let it go, lol. There has to be a reason for this power failure and I have to find it.

 

[dredd0822]

Another thing: I see in the EEC pinout diagram that the pink/black wire comes from a fuse link D. Where exactly is this fuse link in my car?

 

[jozsefsz]

The dark green wire is being fed by the incoming pink & black wire. Which you've verified is good, producing a constant 12V.
I'm likewise a computer guy (solution architect), so I completely get where you're coming from. I've also been working on cars for 30 years give-or-take, and I've had my '95 for 20 years too.

The relay in the CCRM is a simple switch which is activated by voltage, + on one side, - on the other. The EEC relay inside the CCRM gives the + voltage to the switch. If you want to verify that the EEC relay is getting good voltage, you should be getting 12v when the ignition switch is on at the red & green wire coming into the CCRM (on pin 13). It must be though, because otherwise the car wouldn't run at all when the fuel pump was jumpered.

The - (ground) to the switch is provided by the PCM itself on the light-blue wire (or when you manually ground it from the test port). So that, in combination with the ignition switch which activates the PCM relay, is what controls whether the fuel pump relay (switch) is on.

You could try grounding directly from the light-blue wire as it enters the CCRM to battery negative to see if the darned thing activates and you get good voltage on dark green. That would track the problem to the ground circuit to the PCM. You previously jumpered at the test port, which would have caused it to work even if the PCM had a problem, but it doesn't ensure that the ground connection was making it all the way back to the CCRM.

When everything is right and the switch is "on", the relay is activated, it just connects the pink & black wire to the dark green wire.

So long story short, the problem is going to be either the ground wire coming from the CCRM back to the PCM / Test Port (light blue), or a physical problem with the dark green wire's pin (corrosion, bent, broken, melted). Focus on those two and I think you'll find the problem.

 

[jozsefsz]

And as you mention the aftermarket security system, there's a huge possibility that it's the problem (as a future note that's really good information to provide right away, those darned things are the source of issues 99% of the time), and it's interrupting the ground wire from the PCM to the CCRM. Look to see if they've hacked into a light blue & orange wire (I'd put money on it).

Disabling the fuel pump, ignition, or starter wire are how security systems typically operate. And if a relay inside the alarm unit went bad, or someone carelessly connected the wires, you'll get what you have.

 

[dredd0822]

Ok jozsefsz, I'm an idiot.

So I was looking at this 94-95 EEC and CCRM diagrams ('94-'95 Mustang EEC and CCRM Diagrams and if you look at the PCM - CCRM color diagrams in that discussion thread (4 total, but the first three are the ones that go from PCM to fuel pump function), I noticed that there are actually three wires that are orange and light blue, two that power the HEDF relay, and the one that powers the Fuel Pump relay.

So, it turns out that I had been testing the wrong orange/light blue wire

I finally found the right light blue/orange wire on the CCRM connector, and when I applied my volt tester to it, there's nothing happening.
By following the diagrams provided in that other discussion thread, the light blue/orange wire goes from the PCM, splits off to the VIP test connector, and to the CCRM.
When I tested the wire by the test connector, there was also no ground. (I think this is why, when I had jumped the test connector in a previous test, the fuel pump still had not come on.)
Now, I didn't have someone with me, so I did these latest tests without turning the key to the On position, so I'm not sure if that was a valid test. Can you confirm?

Also, one other thing I noticed: By looking at these diagrams, I noticed that the dark green/yellow wire, on the way from the PCM to the CCRM, breaks off and connects to the Inertia Switch. There's two wires that connect to the inertia switch in the back, one looks green, and one is brown.
When I tested the green wire, it had power to it. When I tested the brown wire, there was nothing. When I supplied voltage to the brown wire, the pump came on.

I also looked at the alarm setup underneath the dash. First off, I triggered the alarm, then successfully overrode it, but the car still did not start after that. It seems that the alarm was connected to two wires, one yellow and one beige color, out of the ignition switch. So I'm not sure that it's the alarm system that's causing the problem, but I don't know what those wires are either, so I could still be wrong there.

What can you deduce from everything I just described?