Odd no start '95 MTX

[Greg Corcoran]

TLDR version - various no start conditions across a three week period. sometimes no crank, once mimics a dying battery with slow crank.

Maybe my SHO doesn't like being on winter duty, but it's started a hard to diagnose no start condition because the only thing consistent is no start until it's good and ready to cooperate... Can't find anything like it in the archives, or I maybe don't know how to write a proper search query.

First instance - 45 minute interstate drive home from the airport after a week out of town. Stopped to run an errand as I got into town. Car sat maybe 8-10 minutes, turn the key, Slow turning over maybe twice "Grurh Grugh, click" Try again rapid stuttering clicks. Hmmmn - dead battery after a 45 minute highway drive? Inconceivable! Called wifey to bring her car and the jumper cables. Just for grins while I was bored waiting, I tried again, maybe 10 minutes later and it fired right up. Not a dead battery? and awfully fast for a bad starter/ heat soak problem to cool off.

Only drove the car once or twice the next two weeks, local errands, no issues.

Second instance running errands Saturday first stop a mile from home, 2 -3 minutes inside, no restart issues; second stop 15 minute city driving, 20 minutes in store, no issues; third stop, another 15 minutes driving, maybe 40-45 minutes inside, No Crank no noise, but I'm parked on a slight grade. Roll and pop clutch, fires right up. One errand left and it's the only one I promised my wife I'd take care of... So I had to make the last stop.
4th stop 15 minutes driving, 3-4 minute stop, again no crank, no noise at all, and no start. Lights, radio, sunroof, everything works but the starter. I thought I had parked on a slight grade this time too, but not enough to get the car to roll on its own. That's OK, after the 1st incident 2 weeks ago I put the jumper pack we keep my wife's car into the SHO. BUT Won't take a jump and diagnostic LEDs on the jump pack tell me there is insufficient juice available in the jump pack even though the other LEDs tell me it's fully charged. Bad starter w/ internal short maybe want too much current? Bad battery cable - internal corrosion and high voltage drop wanting too much current? Call wife to ask her to bring some tools so I can take the battery out and get it checked at NAPA, clean the terminals, etc. I try the starter 2 or 3 more times every 5 minutes or so, no change. Wife finally arrives after 30 minutes I try the car one last time before I start pulling the battery out ... and it fires right up.

Cleaned the battery terminals after I got it home even though they looked fine, cleaned the ground to the fender even though it looked fine, put the front up on jackstands and checked the cables at the starter, Tight, but the plastic/bakelite end of the starter solenoid moved when I tugged on the positive cable. AHA, bad solenoid? The plastic end cap with the 12V battery terminal moving could explain the problem?

I have a spare starter from my former '92 SHO. So pull the '95 starter and see the starter gear between the 92 and 95 is different. Can't use the '92 starter, or at least I don't want to try since it is visibly different gear, But I swap the solenoids and put the old starter back in with an intact solenoid. Fires right up. Turn it off and on 2 more times in a row to heat the starter and solenoid up as fast as I can to stress test it. Everything's great. Go inside an apologize for working on my car on Valentine's day. She was amazingly gracious about it.

Sunday - need to go to the airport. No start no crank, lights radio, sunroof all work... WTF!?!?!! Put it in 5th and push it back about 2 feet. Not sure why that occurred to me. Anyway - Fired right up. Got to the airport. Just for morbid curiosity I tried to start it. Nope. Now I'm sitting in a hotel room after work trying to troubleshoot remotely...

The initial slow turn over/ no start several weeks ago is a piece I'm having trouble fitting into the other no starts. The sometimes it happens engine hot, sometimes engine cold is also odd.

My best guess is bad starter motor, but I can't rule out some other things like:
-Maybe the clutch safety switch? that would be no start, no clicking too, right? But not the first slow turnover
-Failing Ignition switch, also could be no start? But could that be the slow turn over from the first event?
-Bad battery cables (internal corrosion?) That can be temperature dependent. What should the resistance be? or do I need to do a voltage drop test?

And why would the starter motor end gear be different between a '92 and a '95 MTX? They are both an F3 prefix, but one is a -AA (smaller gear) and one is AB suffix (larger gear). Both are rebuilt units.

 

[luigisho]

My F-150 starter gave me all sorts of different forms of nothing with key turn, slow crank, etc. I'm not a shoot the parts cannon person but on more affordable parts vs time spent I would consider throwing a new starter on it after I was sure the battery and alt were functioning properly. Your other guesses are good.

 

[zoomlater]

92 starters had a different tooth count, I think it was 10 compared to the later ones have 12. It was a known issue on the 92 that drove a change to the 12 tooth. There was a Ford TSB for it.

3.2L Starter compatible with the 3.0L?

Hey All, Could someone please clarify if starters from the 3.2L ATX engines are 100% compatible / functional on the 3.0L MTX engines? (Mods: My apologies if this should have been posted in Electrical & Audio section.) Thanks! -Mike

shoforum.com

 

[fcable]

Take your voltmeter and connect directly to the starter solenoid engage wire and the engine block. When the no crank problem occurs, what voltage do you get?

Sent from my SM-A166U using Tapatalk

 

[Greg Corcoran]

Take your voltmeter and connect directly to the starter solenoid engage wire and the engine block. When the no crank problem occurs, what voltage do you get?

Sent from my SM-A166U using Tapatalk

I can try that when I get back home. I would think I'd see 12V unless bad Clutch or ignition switch. @fcable Is there something else you're thinking?

 

[SHO@Sparks]

Good thoughts and possibilities.

When attempting to start it you can perform voltage drop tests in different areas of the power and ground sides to see where the excessive voltage drop occurs when it fails to crank.

You can also wire a headlamp bulb in the starter key feed crank signal side to see whether you can carry a load to the crank signal of the starter. This can give you a quick visual either when the bulb lights or doesn't light when you're trying to start it.

If you thought it was the clutch pedal switch, you can disconnect and bypass the switch by jumpering the circuits to see if the concerns repeat. Just do it for testing purposes, realizing that the vehicle will now be able to be started in gear, so don't forgot to have it in neutral.

Hope this is helpful.


Mike

 

[Greg Corcoran]

Take your voltmeter and connect directly to the starter solenoid engage wire and the engine block. When the no crank problem occurs, what voltage do you get?

Sent from my SM-A166U using Tapatalk

11 to 11.2 volts with starts, 10.1 and 9.9 no starts. So, what then? There enough drop in 1 volt to not pull in the solenoid? Wouldn’t the solenoid just pull more amps? It looks like a 10 or 12 gauge wire. I would expect higher voltage drop with heated wiring.
Oh, and this reading was to the negative post of the battery not the block.

 

[BaySHO Performance]

Doubt if you will find anything, but I suggest you check the codes:

EEC Self Test Procedure - V6SHO

wiki.wikisho.com

And just for jollies, the wiring diagram for a '94 (same as 93) included.
To check the clutch switch, you could connect a remote starter between the solenoid wire and B+ wire and turn the ignition on. to see if it will start. Be aware that will throw a code 528 clutch switch circuit failure which can be ignored.

 

[fcable]

11 to 11.2 volts with starts, 10.1 and 9.9 no starts. So, what then? There enough drop in 1 volt to not pull in the solenoid? Wouldn’t the solenoid just pull more amps? It looks like a 10 or 12 gauge wire. I would expect higher voltage drop with heated wiring.
Oh, and this reading was to the negative post of the battery not the block.

Measure from block to starter solenoid engage wire. That assures you have good ground to block from battery. The solenoid should pull in with 10v

 

[FastCAD]

The first part of your intermittent or no start symptoms sounds like the classic failing of a crank sensor. With your multi meter check the ohms going to the DIS (minimum 10 ohms key on) it's quick an easy (see attached).
The slow starter could be just excessive battery drain from multiple cranking. Keep your battery charged up. Check the starter relay for (12v) driver's fender make sure all grounds (black wires) are secure also.
In a no start condition, you can test the CCRM (key on) for voltage in and out, but I believe your pin out chart is different from my GEN1.
Testing is much cheaper than throwing in parts.
Best to Ya

 

[Greg Corcoran]

Doubt if you will find anything, but I suggest you check the codes:

EEC Self Test Procedure - V6SHO

wiki.wikisho.com

And just for jollies, the wiring diagram for a '94 (same as 93) included.View attachment 96737
To check the clutch switch, you could connect a remote starter between the solenoid wire and B+ wire and turn the ignition on. to see if it will start. Be aware that will throw a code 528 clutch switch circuit failure which can be ignored.

I haven’t pulled codes but I can get KOEO I expect. Since it fairly reliably won’t start hot, KOER might be a challenge.
But I’m a bit curious about the clutch switch piece. Since I can get a voltage at the solenoid when I get a no start, doesn’t that exonerate the clutch switch? I would think the ~1 volt drop between start/no start is from the engine and wiring being warm?

 

[BaySHO Performance]

I haven’t pulled codes but I can get KOEO I expect. Since it fairly reliably won’t start hot, KOER might be a challenge.
But I’m a bit curious about the clutch switch piece. Since I can get a voltage at the solenoid when I get a no start, doesn’t that exonerate the clutch switch? I would think the ~1 volt drop between start/no start is from the engine and wiring being warm?

KOEO is what you want. No need for KOER. Yes, clutch switch exonerated.

 

[Greg Corcoran]

KOEO is what you want. No need for KOER. Yes, clutch switch exonerated.

539 is the only code. I had the AC on when I was out driving today, so my bad. It's 65 today in Colorado. We want, desperately need, the snow the NE is getting today...

528 is only saved code, but that was likely me screwing around with troubleshooting. I put it to 'start' and then pressed the clutch pedal and it started when cold.With engine warmed up and no start, start position first then clutch pedal pressed still a no start. That test was several days ago before the voltage readings reported above.

 

[Greg Corcoran]

The first part of your intermittent or no start symptoms sounds like the classic failing of a crank sensor. With your multi meter check the ohms going to the DIS (minimum 10 ohms key on) it's quick an easy (see attached).

I've been lucky enough not to fry a crank sensor since about 1997, but if IIRC it would crank, but not start? And this would be after dying in the middle of driving someplace, just quit, and not restart for hours until it cooled down... That's not what I'm seeing. Can you point to a crank sensor failure thread that matches what I'm describing? Maybe I was 'lucky' last time? Also I "think" you forgot a k in the resistance value? shouldn't it be 10K ohm minimum and why key on? The crank sensor is disconnected and unpowered at that point?

 

[BaySHO Performance]

Those codes rule out a bad CPS, as suggested.

 

[Greg Corcoran]

Those codes rule out a bad CPS, as suggested.

Thanks! So I’m down to:
•intermittent bad ground mostly when hot, but sometimes when stone cold, or
•bad starter.

I still need to do the @fcable voltage drop to the block not the battery negative terminal. I acknowledge I’m not an electrician, But if I’m 12.5-12.6 across the battery terminals, and 9.9 to the neg post when no start I’m a bit at a loss what the drop to the block is going to tell me. Won’t it have to be something between 9.9 (no start value) and 11 (start reading) from above? Or is there some way for the value to be less than 9.9 But then it picks up voltage by the time it hits the negative terminal?

 

[SHO@Sparks]

Sharing this video on how to voltage drop test a starting circuit, as it may be helpful at clearing up some of your questions. Just to add notice that when you perform a voltage drop test, you're not checking off of the positive and negative like testing at the battery. You're checking either the positive, power side of the circuit and another positive or the negative, ground side of the circuit and another ground. Voltage drop testing is performed on a circuit when it's being loaded, like trying to crank it to start. It can be confusing to some, understandably.

Additionally, if your only having a slow crank or no crank issue, that shouldn't be related to your crank sensor. If you had no crank sensor input to the PCM, it would cause a crank no start concern.

If you look at the electrical schematic picture supplied by BaySHO Performance above, you can see the the ignition switch feeds the clutch switch and then from there it feeds the starter solenoid and the the Ignition Control Module from Splice 181 on circuit 32 R/LB. As an example, there could be corrosion on the left side of the splice only to the starter and not to the Ignition Control Module.

Hope this is helpful.

 

[Greg Corcoran]

So I’m down to:
•intermittent bad ground mostly when hot, but sometimes when stone cold, or
•bad starter.

I still need to do the @fcable voltage drop to the block not the battery negative terminal.

OK, here's a table of what I found.On first crank it started, then no crank the remainder of the testing. The crank and start was 11.2 V solenoid trigger to negative battery clamp, same set up as yesterday. I was hoping to get several readings with crank and start since engine was cooled off, but nope. This repeat of yesterday was intended to compare baselines...

All readings with a 25+ year old Craftsman digital multi-meter set to 20VDC scale. After first start, all remaining attempts were no crank when ignition switch in "start" position, engine cool (sitting for 4.5 hours in garage). And the last piece of data - when I started the voltage across the battery clamps and the terminals was identical @12.56 V, when I finished it was 12.31. With just the one brief crank and start shouldn't it have stayed closer to the initial 12.56? The battery is a 14 months old NAPA Legend, allegedly a 72 month battery.

Description	Key Off	Key in "start" but no crank
Positive cable (Battery clamp to B+ Solenoid)	0.02	0.04
Solenoid B+ to starter solenoid trigger wire	12.32	1.21
Starter Solenoid trigger to engine block	0.02	10.57

I should maybe also note as part of recent trouble shooting, immediately after a successful crank and start the voltage at the battery was 14.8V (the second decimal point was moving up and down a little 14.82- 14.87). I checked the running battery voltage because one of the older threads mentioned bad alternator as a possibility.

So at this point I'm thinking Starter but the battery voltage after testing does have me a little confused.

 

[FastCAD]

That crank sensor is still showing failure. At first, you had intermittent start for maybe a few times, but then it's no start, and that's where you are at now. My cranks sensors have had a life span of (average) 75k miles, but my SHO is a daily driver w/250Kmiles. If you have had a crank sensor since 1997 then that is either a world record or very low miles. LOL! You can't chase a ghost. The (minimum) 10 ohms at the DIS in the key on/run position not start position and that is a crucial signal as far as the PCM is concerned. Then it's the cam sensor and then all the other signals from the CCRM. Without these signals, the PCM will not allow start. Have you verified 12v at the starter relay on the driver's fender? That relay also provides power to the CCRM which provides all the other signals to the PCM to allow start. If the CCRM is corrupt, then the PCM will not receive a start condition. This is why many SHO owners have PCM/CCRM backups. Just swap out a known good backup to identify the problem and when found just replace the backup for later troubleshooting, and you can stop the time-consuming and aggravating chase.

 

[SHO@Sparks]

Greg,

I just reread your initial post and I didn't see where you mentioned having a normal cranking, but with a no start issue on your SHO, as FastCAD seemed to mention above.

Maybe I missed that?

I thought that your concern was always that it would be a slow crank/no start or it won't crank at all, resulting in a no start concern.

Can you confirm what issues your SHO is experiencing?

Basically, is it a very slow crank or no crank issue, resulting in a no start issue?

Or.......

Is it an intermittent cranks and won't start?

They are 2 different scenarios in general and people can describe them differently.

Hope that makes sense.