issa_blu3v

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Hello, I have a 2008 mustang GT premium. Was looking for a possible solution to a problem that is occurring. Had an issue with starting sometimes it would start fine then other times nothing at all. The car has full power and EVERYTHING works, The best way I can describe the issue, is that its basically like trying to start the car without pushing the clutch in. And my first thought was obviously the clutch switch had gone bad, it didn't. The clutch switch is functioning and I verified with a scan tool its "depressing" as well as jumped the switch together to bypass and still nothing. I also checked the top sensor it shows as working too. I also had a security / antitheft issue before with keys but I was able to resolve the issues with an Autel scanner I have, and programmed the new keys no problem. The car would start normally sometimes and run just fine but after driving and getting it to full operating temp I would turn it off and not get it to start for at least another hour, if at all that day. all 3 of my keys started the car at least once if not more so I don't suspect my anti theft to be the cause. Now the car is inoperable and hasn't started or moved for almost a week nothing I've done has worked. I've checked all fuses / relays and grounds they checked out good and the car also has no DTC codes or a CEL. I've also done a voltage drop test across the starter and it was within spec no drop. Jumped the starter and it was working fine as well as the relay. I then checked fuse 21 in the passenger kick panel and with key cranking there and was voltage in the correct places. I then tested the clutch switch connector because that's where power goes next and there was no power when key cranking or in RUN. I'm suspecting the wiring for the clutch switch has a issue but before I start tearing shit apart let me know what yall think.

I know it will not be the battery, Ignition switch, PATs Immobilizer, or fuses. let me also be clear on this, it does not have a drivability issue, if it somehow starts I can beat on it all day no issues at all when driving but the second I turn it off it almost never starts again.
 

Midlife Crises

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There are two switches in the clutch circuit. One normally open and one normally closed. If I remember correctly they both connect to chassis ground and do not have “power” on them. Test the switches for continuity.
 

Juice

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15 yr old car. Ever replace the starter?
 

moooosestang

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Sounds like the starter is having an issue when hot. If it always happens when it's hot then it's most likely the starter. you could try shielding the starter and see if the problem goes away. How many miles is on the car? You only get so many cranks out of a starter.
 

JC SSP

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Sounds like an intermittent elec issue, bad ground, heat generated or starter is going bad.

Not trying to be smart… but have you tried to “push start” the car and see if the engines runs?
 
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DieHarder

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Assuming you have a wiring diagram or one online.... chase "why" it's not starting. If the problem is heat related it's likely in the engine bay. That said, suggest first tracing the circuit to verify continuity; voltages/ grounds/relays/fuses and disconnect/check/clean/reconnect all of the connectors in the circuit. If you don't see something you're expecting (continuity/voltage/ground) trace out to determine cause. Try swapping relays where you can to eliminate active component issues.

https://iihs.net/fsm/?d=40&f=Starting System.pdf&p=2

https://iihs.net/fsm/?d=143 (See starting system)

Here's a good explanation of the circuit.


And


As indicated in the video you can do a quick test of the clutch switch by putting the car in neutral - push the switch in and turn the key. If it starts the clutch switch may be misadjusted. Worth trying anyway.
 
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issa_blu3v

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Thanks for the replies everyone I will be doing more testing later tonight, I've jumped the starter with power and it turns over the engine no problem. the car has about 106,000 miles on it and it is modified. Ive adjusted the clutch switch and even pressing by hand the car wont start. ive swapped relays and fuses and Im pretty sure its wiring related so ill check it out later tonight and let yall know.
 

JC SSP

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When the starter turns does the engine start as normal?

If yes, then you’re looking for something between the starter and ignition key (harness, relays, switches etc).

If not, then you have a potentially more complicated issue. Check fuel pump, injectors, etc.

An engine needs three basic things to run… air, fuel and spark. It has to be one or more of these.
 

issa_blu3v

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No I didn't sit and let it crank I just bumped it over a few times to test it, but I will be trying that later. for some reason trying to start it like that went right over my head. I was also thinking about bump starting it once my friend can push it later tonight.
 

issa_blu3v

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Ok just tested and my god how did I not figure this out when I bumped it... It started right up when I jumped the starter fully with key in run so that helps a ton in diagnosing. Any recommendations for first step on ignition to starter wiring ?
 

DieHarder

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Ok just tested and my god how did I not figure this out when I bumped it... It started right up when I jumped the starter fully with key in run so that helps a ton in diagnosing. Any recommendations for first step on ignition to starter wiring ?

I then checked fuse 21 in the passenger kick panel and with key cranking there and was voltage in the correct places. I then tested the clutch switch connector because that's where power goes next and there was no power when key cranking or in RUN. I'm suspecting the wiring for the clutch switch has a issue but before I start tearing shit apart let me know what yall think.

Review the videos again; read/understand how the circuit works (second manual link) and follow the troubleshooting procedures (Pinpoint tests) in the manual. You need to determine if the starter relay has all of the inputs it needs to energize or not and why. If the starter relay activates as it should move onto verifying connectivity to the starter and the clutch interlock. The idea is to troubleshoot down to likely culprits and isolate from there. Once you find an area that doesn't work per the manual chase down why. Good luck.
 

Jello_08GT

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Hello, I have a 2008 mustang GT premium. Was looking for a possible solution to a problem that is occurring. Had an issue with starting sometimes it would start fine then other times nothing at all. The car has full power and EVERYTHING works, The best way I can describe the issue, is that its basically like trying to start the car without pushing the clutch in. And my first thought was obviously the clutch switch had gone bad, it didn't. The clutch switch is functioning and I verified with a scan tool its "depressing" as well as jumped the switch together to bypass and still nothing. I also checked the top sensor it shows as working too. I also had a security / antitheft issue before with keys but I was able to resolve the issues with an Autel scanner I have, and programmed the new keys no problem. The car would start normally sometimes and run just fine but after driving and getting it to full operating temp I would turn it off and not get it to start for at least another hour, if at all that day. all 3 of my keys started the car at least once if not more so I don't suspect my anti theft to be the cause. Now the car is inoperable and hasn't started or moved for almost a week nothing I've done has worked. I've checked all fuses / relays and grounds they checked out good and the car also has no DTC codes or a CEL. I've also done a voltage drop test across the starter and it was within spec no drop. Jumped the starter and it was working fine as well as the relay. I then checked fuse 21 in the passenger kick panel and with key cranking there and was voltage in the correct places. I then tested the clutch switch connector because that's where power goes next and there was no power when key cranking or in RUN. I'm suspecting the wiring for the clutch switch has a issue but before I start tearing shit apart let me know what yall think.

I know it will not be the battery, Ignition switch, PATs Immobilizer, or fuses. let me also be clear on this, it does not have a drivability issue, if it somehow starts I can beat on it all day no issues at all when driving but the second I turn it off it almost never starts again.
Hey there, we've got the exact same car – an '08 GT/CS with 120K miles. Weirdly, I've been dealing with the same issue for the past couple of years, and as unfortunate as it is, it's kind of comforting to find someone else going through the same struggle.

I've checked everything:
- Alternator is good
- Battery is good
- Starter is good
- Brand new ignition switch
- Clutch safety switch is good (even tried bypassing it)
- Fuses are good
- Relay is good
- SJB by the passenger side is clean, not a speck of dust
- ECU has no corrosion, all pins are solid
- Grounds are all good (added extra ones for a beefy audio system)
- Keys are good, and I even have a spare

Despite all that, my car runs fine until I decide to go buy some steaks to grill. Then, I'm stuck in a parking lot, cursing and pushing the car to start it manually.

I'm really at a loss here. I've even resorted to installing a push switch inside to jump the positive to the starter relay pin, so I don't have to mess around under the hood with a wire every time.

From my troubleshooting, it seems like there's a fault between the clutch safety switch and the relay pin that's supposed to be energized. Trying to find it in the mess of cables is a nightmare. The ground from the computer is good, indicating the car is ready to turn on, but the positive pin just isn't getting the power it needs.

I know it's been a while, but did you manage to fix it? Or does anyone else have more clues?

Thanks a bunch.
 

satellitemanNZ

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Jello - the above post is similiar to my 2009 45th Anv 4.6 GT/ - i travel abroad for alot of work these days. After returning to a near flat battery once before, ( the car did try to start & and after recharging the battery it was fine ) ..But this trip like 6months later - it had been out for a whole day of running and i parked it in the garage and removed the -Ve terminal off the battery post because i knew id be away nearly 3 months in africa. So i get back a few days ago - i give the batter a trickle up for 1/2 and hour and notice its looking really healthy , littel current draw and a nice brite green indicator inside the 450 CCA battery. I replace the battery terminal . Crank the car expecting it to start , but it simply cranked for seemingly ever. I stopped short of 10 second continous crank , it would usually fire in less than 1 second previously. I released the key , and tried again , this time NO CRANK ! ...and its never cranked again !
Battery is strong , if i hot wire the starter it cranks like its got no compression it spins that fast ...the battery is mint condition.
Clutch switch was removed and checked....tested with DMM and also extended it stroke and fitted then auto length adjusted by pressing the clutch pedal.
With Key in start postion , i get PCM relay coming on and +12vdc get supplied to PCM B connector B35, B36, B45.
The Starter relat is getting a 12vdc supply when the Clutch is engaged, and the only thing that is not happening is the Starter Relay isnt being grounded via the PCM internal transistor. ( logic controlled or failure of some kind )
The wiring to the PCM harness connector has been checked and pinned out. I happy with what i have checked.
I can confirm that IF i have PATS , then the Keys ( i have tried two fobs ) .. are accepted according to the dash. ..the Padlock goes away after swithing to Ignition ON and waiting a few seconds .
I have one distrubing situation .. I know my OBD2 scanner used to connect ( although i only ever did it once 10 years ago ) it certainly does not connect to any module at all ..and says check the link plug etc. I have done a Pin test with ford service manual. I dont get >10vdc on pins it says you should , but i have +2.5 vdc ..and according to the Can bus comms , i think thats correct ...its a idle state - but it certainly doesnt work & that troubles me.
Also the dash seems to indicate with a system test that it does know how to communicate as it returned that doors , trunk , fuel cap were ok . It does state there is a Charging system fault ( lord knows why it can say this when the car hasnt even run yet ) . I also says Odometer data error and Fuel Low warning - BUT i suspect the fuel low warning is because the trip meter is all dashes and it has no way to determine yet an estimated amount of fuel left in the tank. I have 3/4 full tank acording to the analog meter.
So right now, i simply dont know what to do. Im in NZ and there are a few of these GT's on the road, but as for a local ford agent being able to service it, im not feeling confident. I really want to see if any code is sitting onboard the system and needs to be cleared to allow the Starter relay and Fuel Injection control to become active, but my feeling is some how the PCM unit has gone dumb , yet its supposed to have an EEPROM in it that unless exposed to UV light etc it cant loose its data. Worse still if i need a new PCM or try one, i will need to find the tools for Ford NZ to able to get the VIN data and general engine cal data transfered.
So i have exhausted my efforts apart from a thread seen on another forum about some type of alarm module being related under the dash behind the glovebox next to a blower motor ..and it can be removed or bypoassed some how...yet according t the info i have from the service manuals , this isnt existing or in the diagnostic charts/check sheets.
Any ideas people? Remember , this battery is like new in condition and right now its at 13.33vdc after charging it.
Cheers Stu in New Zealand
 

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