Car Doesn't Start Randomly - Think it's actually 2 problems...

[vipergts281]

UPDATE: It was the alternator causing the battery light to come on. More updates found below in post #11.


TL;DR

Car has 192,922 miles on it.

Car randomly doesn't start, been going on for months, tried new battery and new battery clamps, didn't help

Did a test and found out the PCM/instrument cluster circuit has a parasitic draw

Battery light started coming on and off randomly a few weeks ago



Been having problems getting the car to start. Sometimes it starts, sometimes it doesn't. And even when it does start, sometimes I have to turn the key and keep it there for a few seconds until the car starts up. Not because of weak cranking, just would go from nothing to firing up regularly.

Replaced the battery wire clamps since they were original and they weren't as tight as they could have been. Still had the problem. Put a new battery in, still had the problem.

Since then, my battery light randomly comes on now (started a few weeks ago, long after the initial car not starting problem). It will go off after being on for several minutes. It usually comes on 5-10 minutes after driving. Other than that, no other noticeable patterns.

Figured a wire may be loose, but hitting bumps vs smooth roads doesn't affect the light plus it comes on when the car is sitting still (although I guess vibration could be a culprit). Just seems to come on and off whenever it wants. Was just in my garage troubleshooting and it came on then went off after a minute. Then a minute later came on again until I turned my car off 5 minutes later.

I also have a draw on the battery. After hooking up a testing light, found out it's the 40 amp fuse that controls the instrument cluster and PCM.

So the car not starting sometimes would appear to be because of the parasitic drain. But, doesn't explain the battery light coming on. Which points to the alternator and it's just a coincidence that it's happening while having the car not starting problems. Although again, the not starting problem has been around for months, long before the light ever came on.

Just did some voltage testing:

Engine Running - 13.9
Turned headlights on - 13.8
Battery light came on - 13.8
12.5 when fans kicked on and then 12.2...headlights, ac, and rear defroster were on at this point as well.
Fan went off and went to 12.5
Let car run a few minutes and turned it off at 12.6.

After sitting for a little it drops to 12.2-12.3 which is why, I'd assume, it has trouble starting.

I currently have the fuse pulled that was drawing power, going to check the voltage tonight after it sits for a few hours. If it's at 12.6 then I know it was drawing enough power to not start the car.

ADDITIONAL NOTES:
My meter doesn't have DC amps so I couldn't test the amount of parasitic draw.

When driving, the battery light will go back off after a bit.

I still need to crawl under the car and make sure the wires going to the alternator aren't loose.

I took the kick panel off to get access tot eh PCM and made sure no wires were loose, which they didn't appear to be. But besides that, I have no idea what to do/look for.

I also have a slight misfire I've been trying to figure out/fix. Maybe that's related to all of this...not getting enough voltage/power?? Alternator?



QUESTIONs:
If the alternator is going bad, it's still a possibility that it will charge the battery at some times but not others?

Since the PCM and instrument cluster are drawing power when the car is off, does this mean one of them is bad? Or is there something else I can do to test things?


Hate to think about it, but I'm thinking my alternator is on it's last leg. This would be #4 or so, I lost count.

 

[rattle_snake]

QUESTIONs:
If the alternator is going bad, it's still a possibility that it will charge the battery at some times but not others?

Since the PCM and instrument cluster are drawing power when the car is off, does this mean one of them is bad? Or is there something else I can do to test things?

Yes, alternator can still be a problem, especially at WOT. If you can datalog, log the battery voltage.

Yes the PCM/IC will draw a little current key off. not much, need to measure. surprised your meter won't do DCA.

When you say no start; is it no crank, or crank but no start? Next step is schematic and check relays.

 

[vipergts281]

Yes, alternator can still be a problem, especially at WOT. If you can datalog, log the battery voltage.

I have a Predator, so I can use that.

What am I looking for exactly? What the voltage is at WOT and/or driving?

Yes the PCM/IC will draw a little current key off. not much, need to measure. surprised your meter won't do DCA.

It's an old meter I got when I used to be an electrician, so I'm sure it was geared toward residential homes...which is AC.

When you say no start; is it no crank, or crank but no start? Next step is schematic and check relays.

As in turn the key and besides me hearing the fuel pump and a click, nothing else happens.

To get it to start, I have to hold the key in the on position for a good 5 seconds (sometimes longer sometimes shorter) and it fires right up. Once it starts to fire up, it never struggles to crank over. It just starts like it normally would, literally the only difference being holding the key in the on position for a few seconds.

 

[apex svt]

As far as the starting thing I had this happen to me ony 01 where the stater relay wasn't making good connection I bent the prongs in the fuse box in with a little screw driver to tighten it up.
An easy check for the alternator is to turn the key all the way forward (without starting) and hold a wrench to the pulley/nut and if its magnetic its still good. Hope you find the problem!

 

[vipergts281]

As far as the starting thing I had this happen to me ony 01 where the stater relay wasn't making good connection I bent the prongs in the fuse box in with a little screw driver to tighten it up.
An easy check for the alternator is to turn the key all the way forward (without starting) and hold a wrench to the pulley/nut and if its magnetic its still good. Hope you find the problem!

Thanks for the post/tips. I'll give them a try tomorrow.

 

[vipergts281]

An easy check for the alternator is to turn the key all the way forward (without starting) and hold a wrench to the pulley/nut and if its magnetic its still good. Hope you find the problem!

Did this test and it was magnetic. It was magnetic before turning the key and stayed the same magnetic power wise, after turning the key.

Going to check out the relay today and see if the prongs may be loose.

 

[vipergts281]

Just updating for future reference in case anyone comes across this while searching...

I got under the car and checked the connections at the alternator and where the ground wire connects to the engine mount bolt. All were tight, no obvious signs of fraying or anything like that. I also cleaned up the connection where the wire connects to the alternator, under the rubber boot.

Then I cleaned up the 3 ground connections on the front of the car, near the headlights.

Bought a battery tender and had the car hooked up last night so the battery was fully charged.

Went for a drive today and the car felt better. I don't know if my mind was playing tricks on me or not, but the car just felt like it drove a little better. Perhaps the battery hasn't been fully charged in a bit and/or the ground connection cleaning did something?? Car didn't seem to misfire either (it was very slight before), so maybe this whole time it's been a battery voltage problem? Need to drive it more to see for sure.

Mainly I was hoping the battery light wouldn't come on. Drove for about 8 minutes to a store, no light. There's hope! 20 minutes later started driving home and the light came on about 2 minutes into the drive and stayed on for the remaining 5 minutes or so until I got home.

I may just buy a new alternator and see if that fixes everything. I'm tired of dealing with this. But at the same time throwing money at something that may not fix the problem isn't the smartest idea either.



As for the car not randomly starting, I'm 99% sure it was because the voltage was too low (was usually around 12.3) after sitting for a bit. Waiting on the car to be sitting for enough time for everything to power down so I can run a parasitic draw test.

As of now I believe it has something to do with the radio. I pulled 2 fuses (9 and 27) which are the radio and subs and the car started fine. Double checking things before I know for sure though. I recently plugged the fuses back in and I'm now giving it time to see if the voltage drops while sitting.

 

[hotcobra03]

I was going to say alt also...evey time I had battery light come and go it was alt..


maybe alt is tied to hard start...

crazy think I found is start car with key takes a couple cranks..yet when having starter issues push starting car it fires sec motor turns

 

[hotcobra03]

For weird test you can run a jumper to starter and have just key in run position and see if it fires without moving key..

 

[vipergts281]

Thanks for your posts.

I just ordered a new alternator. I'm tired of dealing with this. So hopefully it's the alt.

I'll update the thread once it's installed and I drive the car to test it.

 

[vipergts281]

UPDATE

Installed a new alternator. Drove 40 miles since installing it and the battery light never came on. So that was the culprit on that.
But, I've started the car about 6 times since installing the new alt. The first time it fired right up. The second time there was a slight delay, slight as in like half a second. The third time it wouldn't start for a bit. After about 6 tries it finally fired up, slowly. After that I started it about 3 more times, each time it fired right up normally.

So I don't know what the hell is going on with that (clutch switch, bad relay?). Curious to see if it will continue to act up.

Also, my ABS light that has been on for months, went off after installing the new alternator. But, after about 15 minutes of driving it popped back on and stayed on. Weird.


UPDATE on the update - I've driven hundreds of miles now, all is good with the alternator.

Starting Issue - Didn't happen at all today. But since the last post update, it seems to not be happening as much. Still need to look into it and see what the culprit is. It really is just a random issue, no pattern to it.

 

[Oacevez]

I also had battery light come on

My Cobra has 69,000 and when I ran it on the dyno I notice voltage was about 11.8v. Pulled it out and had it tested, Failed. Replaced and the battery light started coming on intermittently. It turned out that the new alternator was also bad (rebuilt). ABS light was is also on along with Light on the Traction Off Button Switch. This is caused by differences in tire diameter size. Running stock 275 front and 315 in rears, its not much difference, but enough to trigger light. Just take the bulb off the instrument cluster if its bugging you.

As far as checking for current draw. You can use any volt meter that can measure at least 10 amps (any draw higher than 2amps will kill the battery overnight). Put the + of meter to the battery and the - you will put it to the negative cable and disconnect the cable from the battery so that the meter is in series and you get your values. Make sure before you pull the cable off, all doors are closed or latched, no key in the ignition and all consumers are off. If you have a draw, you can start pulling fuses and watch the draw drop, once it does, you can see what the fuse is powering and go from there. I cant see these cars pulling more than 15-20 milli-amps with all systems asleep.

 

[vipergts281]

My Cobra has 69,000 and when I ran it on the dyno....

Sorry, I am just seeing this now. Thank you for taking the time to post and help.

As of now the starting issue is still present...I think. My new alternator took care of the battery problem, as I mentioned before. I thought I had a draw happening but apparently I'm not since I let the car sit for a few days and the battery still showed 12.6 volts.

I have to look into it more, but I'm wondering if my dash cam is drawing a tiny bit. I have it hardwired to power but it shuts off when the car is off, so theoretically it shouldn't be using any power. But, maybe it is for some reason.

To check this I started unplugging the wire into the camera when the car is off. So far, after about 5 starts, the car fires right up. Before that it never went 5 in a row. Going to keep testing this to be sure though.

I barely drive the car anymore (about 500 miles since early November), so I haven't spent much time on this in the past few months.

 

[blk02edge]

My Cobra has 69,000 and when I ran it on the dyno I notice voltage was about 11.8v. Pulled it out and had it tested, Failed. Replaced and the battery light started coming on intermittently. It turned out that the new alternator was also bad (rebuilt). ABS light was is also on along with Light on the Traction Off Button Switch. This is caused by differences in tire diameter size. Running stock 275 front and 315 in rears, its not much difference, but enough to trigger light. Just take the bulb off the instrument cluster if its bugging you.

As far as checking for current draw. You can use any volt meter that can measure at least 10 amps (any draw higher than 2amps will kill the battery overnight). Put the + of meter to the battery and the - you will put it to the negative cable and disconnect the cable from the battery so that the meter is in series and you get your values. Make sure before you pull the cable off, all doors are closed or latched, no key in the ignition and all consumers are off. If you have a draw, you can start pulling fuses and watch the draw drop, once it does, you can see what the fuse is powering and go from there. I cant see these cars pulling more than 15-20 milli-amps with all systems asleep.

Older post but a wider tire will have zero effect on that light, also not any old meter can test DC amps, many do not so you need to find one specifically for it.

OP, my alternator and battery are both getting weak, dips into the high 11's for volts when driving and usually sits at 12.0-12.2v when off but never has an issue starting, to me it really sounds like loose connections or bad relay somewhere to me.

 

[hotcobra03]

Sorry, I am just seeing this now. Thank you for taking the time to post and help.

As of now the starting issue is still present...I think. My new alternator took care of the battery problem, as I mentioned before. I thought I had a draw happening but apparently I'm not since I let the car sit for a few days and the battery still showed 12.6 volts.

I have to look into it more, but I'm wondering if my dash cam is drawing a tiny bit. I have it hardwired to power but it shuts off when the car is off, so theoretically it shouldn't be using any power. But, maybe it is for some reason.

To check this I started unplugging the wire into the camera when the car is off. So far, after about 5 starts, the car fires right up. Before that it never went 5 in a row. Going to keep testing this to be sure though.

I barely drive the car anymore (about 500 miles since early November), so I haven't spent much time on this in the past few months.

Have the coils ever been changed?

I did mine just over 200k..I was getting a miss that just kept getting worse..

I had found a member close by with a good set to try for testing..I never had gotten any codes or service light

 

[vipergts281]

OP, my alternator and battery are both getting weak, dips into the high 11's for volts when driving and usually sits at 12.0-12.2v when off but never has an issue starting, to me it really sounds like loose connections or bad relay somewhere to me.

Interesting, because I was beginning to think the battery was dipping into the low 12's and that may have been causing the non starting issue.

Yes, could definitely be loose connections or a bad relay. I checked for loose connections and didn't find any, but who knows. Could have missed one.

Friend of mine says he thinks it's the starter. I hear the click when I turn the key. He said that's the piece of metal hitting the 2 posts but over time some of the metal wears away, sometimes it makes a good connection and sometimes it doesn't.

At my mileage it could be a number of things.

Thank you for your post.

Have the coils ever been changed?

I did mine just over 200k..I was getting a miss that just kept getting worse..

I had found a member close by with a good set to try for testing..I never had gotten any codes or service light

Not recently. Most are original except for the ones were the plugs blew. They are something I do need to test as they could definitely be the culprit.

That or I'm betting on the spark plugs as being the problem of the misfire. There are still 3 on the passenger side I need to change...the 3 with inserts that I'm paranoid to touch.

 

[blk02edge]

starter could be a good next step. I know how frustrating these things can be, I have been chasing a clunk in my truck that I'm now giving up on till something simply breaks haha

 

[vipergts281]

starter could be a good next step. I know how frustrating these things can be, I have been chasing a clunk in my truck that I'm now giving up on till something simply breaks haha

Yeah, this car is very frustrating anymore. But it's to be expected given the age and mileage.

Good luck with your truck.