Digital Tuning 1995 Mustang Gt Drivabilty Issues And Eec Codes 543 177

mulletmustangs

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Jul 30, 2012
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Hiya all in the Mustang world not new to them put new to the sn95 platform have owned several foxs. So anyways I obtained 95 gt in a trade few months back and been dealing with dudes hacked ass work. So at this point I am chasing my tail I am 99% sure ccrm is bad seeing I have no volt output to stock fan connector I installed two slimlines adjustable fan controller to solve this at first. Well at first after inspection I found car had blown headgasket as well could be the no cooling fan thing huh lol. Well long story short I tore motor down short block installed GT40x heads Crane 1.6 pedestal mount roller rockers , Crane Cam High Energy came stage 1, Ford Racing Intake gaskets,Head Gaskets , ARP Headbolts , Fox Cobra upper and lower intake , AccuFab TB , Pro-M mass air 24lb injectors Adjustable FPR matched set off my fox, BBK shorties new O2 sensor, New TPS, New IAC, All new MSD digital 6, MSD Coil , wire cap rotor. Car is untuned and would rather not bring it to tuner as a basket case.

So after all that I am getting a EEC code 543,177 I found some hacked up wiring in the harness to drivers o2 harness it was wire with grey wire reversed. So my car runs but at times breaks up in lower rpms and I know how set timing spout out at operating temp But if i set timing to 10deg drive home 20 miles from work it will run 195-210 and when I check timing it will be advanced to 20deg back it off do same drive again re check 0 deg wtf. It has stock distributor is the pip bad the ccrm or ecm or both fubard ? Any help would be :leghump:ing awesome!!!!
 
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toyman

SN Certified Technician
Jul 19, 2007
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Sounds like a bad HB. The inner and out rings have/are slipping. Remove belt and see if there is any movement in the HB. There should absolutely be NONE.
The PIP usually die a slow death. Intermittent at first then they just die. The PIP is what signals the ECU for firing the spark to the correct cylinder. Works like a crank sensor.
 

mulletmustangs

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Jul 30, 2012
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i wish it was as simple as the harmonic balancer that is brand new as well. 177 left 02 code is where kid I got car from had wiring to o2 sensor spliced and wrong had volts for heater going ecm signal wire possible spiked ecm and why its giving me all these gremlins . I hate hacks btw
 

toyman

SN Certified Technician
Jul 19, 2007
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If the timing is changing with the spout out the HB is slipping, new or otherwise. Either that or the dizzy hold down bolt is loose.
 

mulletmustangs

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Jul 30, 2012
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Nope no way it is spun I am a ASE cert tech I can figure that out . Did further diag ccrm output fuel pump 9.80 vlts input 12.00 volt I am sure this is my 543 code . Other 177 is from kid fing up left o2 sensor wiring and new o2 is now junk . The timing thing I am going to check by installing known good distributor from my other sn95
 

toyman

SN Certified Technician
Jul 19, 2007
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As the timing is locked with the SPOUT out what do you believe is causing the timing to change by 10* (from 10* to 20*)?
 

mulletmustangs

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Jul 30, 2012
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Well problem has been figured out ! So I hunkered down last night with my DMM in hand and went to it I pretty much already knew gut feeling but wanted to confirm . So anyways after install new CCRM cause old one was out of a 3.8 v6 and not right, so I check voltage again at Dk Grn/Yellow fuel pump wire 9.80 constant volt hmm should only get 12v for 2sec key on to prime then drop zero. Well kid I got car from in trade deal was a moron shorted signal wire to ecm on left side 02 to 5v heated out voltage thus spiking ECM . ECM is putting out 9.8 volts from to 12 ref to monitor fuel pump voltage I got wire at ECM to remove from fuel pump circuit what do you know key on 2 sec 12 volt. So anyways I ordered a new ECM for a 95 cobra and 2 new o2 sensor and a o2 sensor harness from ebay. This would also be why my timing keeps going out of whack as well I may just say f it and install my Hellion turbo kit before winter I already lost alot of summer time it blows my fox is being re done to me 10.5 NHRA rules and is out next season and this sn95 sucks like I recall when I owned a 97 cobra


So if you have a 543 542 code check green yellow from ccrm to see if you have constant 9.8 shorted volts I hate fixing others mistakes its what I do all day long for a living.
 

AudiGary

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Aug 15, 2019
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Well problem has been figured out ! So I hunkered down last night with my DMM in hand and went to it I pretty much already knew gut feeling but wanted to confirm . So anyways after install new CCRM cause old one was out of a 3.8 v6 and not right, so I check voltage again at Dk Grn/Yellow fuel pump wire 9.80 constant volt hmm should only get 12v for 2sec key on to prime then drop zero. Well kid I got car from in trade deal was a moron shorted signal wire to ecm on left side 02 to 5v heated out voltage thus spiking ECM . ECM is putting out 9.8 volts from to 12 ref to monitor fuel pump voltage I got wire at ECM to remove from fuel pump circuit what do you know key on 2 sec 12 volt. So anyways I ordered a new ECM for a 95 cobra and 2 new o2 sensor and a o2 sensor harness from ebay. This would also be why my timing keeps going out of whack as well I may just say f it and install my Hellion turbo kit before winter I already lost alot of summer time it blows my fox is being re done to me 10.5 NHRA rules and is out next season and this sn95 sucks like I recall when I owned a 97 cobra


So if you have a 543 542 code check green yellow from ccrm to see if you have constant 9.8 shorted volts I hate fixing others mistakes its what I do all day long for a living.


I have a 1994 GT that has this EXACT PROBLEM. Thank you for posting this. Maybe a GT maybe originally a 3.8 but it has a T5 and 5.0 in it now.

I kept wondering why I only see 9.8v out of the green yellow wire even wired in a new fuel pump relay to get 13.8-14v at the pump. The pump works again BUT I’m using green/yellow as a trigger wire to terminal 86 on a SPST relay. The relay isn’t closing the coil!

I jumped 30 to 87 on my hot wired relay and the car runs. It runs like absolute garbage. The car also has 24lb injectors and a stock MAF so I ordered fresh 19lb injectors for it. It’s a convertible originally an auto and I believe still has an auto ECU.

Issue is I only get 9.8-10v out of the CCRM even with a new CCRM, albeit a reman CCRM installed.

So the ECU is likely cooked. If you’re still around can you clarify what you did diagnostic wise at the ECU?
 

AudiGary

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Aug 15, 2019
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In my case I found the green yellow wire was shorted to ground somewhere in the rear half of the car. So I undid the harness by ECU validated that it wasn’t shorted at the first half then clipped it to use as a 12v trigger for a hot wired relay to boost pump voltage. I have all new 12 gauge wiring going to the back of the car, and now the green yellow wire isn’t triggering the relay coil. I bet the ECU is cooked from the green yellow short.

Wiring diagram I found shows the ECU branches this yellow green for voltage monitoring I suppose as you say, it’s not just output from the CCRM direct to 12v + at inertia switch.
 

AudiGary

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Aug 15, 2019
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This is a seven year old thread, that member has not been back since.
That's ok, it is the thought that counts!


I know. It was worth a shot.

I cleaned the ground by the ECU and now have 11.5 coming from green yellow at the CCRM and at the harness connector. I sprayed out every connector I could find under the hood. I pulled my ECU and found this:



I bought this car as a basket case. It sure is. This doesn’t look like a modern moates unit.

I suppose there is a custom tune on it.

There is still goo all over the connectors it plugged in.

The ECU lid was loose also. Oh boy!
 

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