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Mike S.
Mike S., ASE Certified Technician
Category: Cadillac
Satisfied Customers: 6793
Experience:  ASE certified
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My problem in a nutshell is that sometimes (not always)

Customer Question

My problem in a nutshell is that sometimes (not always) after driving for about an hour, if I turn off the engine then try to start it in about 15-30 minutes, it will not start. No crank, no turning, etc. But if I come back in like 2 hours, it will start.
So far:
1) my local Cadillac dealership could not properly diagnose the problem. They first reprogrammed my car's computer=did not fix problem.
2) Then told me I needed to replace my ECM=I did that myself but it did not fix the problem
3) then I had them replace the ignition switch=but problem still occurs.
Any idea what it could be? Chip Key? Cylinder lock? Maybe just some bad wiring behind the wheel/dash? Not sure if I just have to abandon any hopes of fixing it and try to get rid of the car.
Also, some said maybe its the fuel pump or EVAP cannister purge solenoid valve?
Not sure if it leads to any help, but do any of these items I came across the internet sound like a possible cause to you:
(1) ASK YOURSELF THE RIGHT QUESTIONS
What happens when you turn the key and try to start the engine?
If the answer is, "Nothing," you should check the battery, battery terminals, battery cables and ignition circuit to make sure voltage is reaching the starter. If the battery is low or has corroded terminals or loose cable connections, the starter may not crank because of low voltage. If the solenoid that energizes the starter motor is faulty or has loose electrical connections, it will prevent the starter from cranking, too. A faulty ignition switch, park/neutral safety switch on the transmission linkage, clutch safety switch on the clutch pedal or a wiring problem are other faults that can also prevent a starter from cranking.
(2) If the battery is low, the next logical step might be to try starting the engine with another battery or a charger. If the engine cranks normally and roars to life, you can assume the problem was a dead battery, or a charging problem that allowed the battery to run down. If the battery accepts a charge and tests okay, checking the output of the charging system should help you identify any problems there.
A charging system that is working properly should produce a charging voltage of somewhere around 14 volts at idle with the lights and accessories off. When the engine is first started, the charging voltage should rise quickly to about two volts above base battery voltage, then taper off, leveling out at the specified voltage. The exact charging voltage will vary according to the battery's state of charge, the load on the electrical system, and temperature. The lower the temperature, the higher the charging voltage. The higher the temperature, the lower the charging voltage. The charging range for a typical alternator might be 13.9 to 14.4 volts at 80 degrees F, but increase to 14.9 to 15.8 volts at subzero temperatures.
If the charging system is not putting out the required voltage, is it the alternator or the regulator? Full fielding the alternator to bypass the regulator should tell you if it is working correctly. Or, take the alternator to a parts store and have it bench tested. If the charging voltage goes up when the regulator is bypassed, the problem is the regulator (or the engine computer in the case of computer-regulated systems). If there is no change in output voltage, the alternator is the culprit.
Many times one or more diodes in the alternator rectifier assembly will have failed, causing a drop in the unit's output. The alternator will still produce current, but not enough to keep the battery fully charged. This type of failure will show up on an oscilloscope as one or more missing humps in the alternator waveform. Most charging system analyzers can detect this type of problem.
Submitted: 1 year ago.
Category: Cadillac
Expert:  Mike S. replied 1 year ago.

It's not the alternator because if the battery was low on charge it would not mysteriously charge itself backup after 2 hours.

What you need to do is purchase an inexpensive voltmeter or at least a 12 volt test light and be prepared to do some testing of the starting system the next time it acts up. It's not going to be the alternator and/or charging system and it's not going to be in the ignition system, as the ignition system is just that, ignition such as spark to the spark plugs, that has nothing to do with cranking the starter over, although voltage does pass through the same ignition switch for both systems.

So, let me know if you have a voltmeter available or when you get one or a 12 volt test light but the voltmeter would be best, ***** *****'ll get the wiring diagram and you will be ready to test the next time it occurs. Or you can just begin twisting and turning each connection in the starting circuit trying to make the problem occur.

Customer: replied 1 year ago.

Tha.is so much. Would you be able to suggest a voltmeter to buy either on Amazon or eBay? Also, can you provide a diagram or instructions tions on where to access the connections to start twist testing? Thank you.

Expert:  Mike S. replied 1 year ago.

Don't you have anything nearby. Amazon or Ebay would have to ship it. Sears, Home Depot, Lowes, Autozone, Advance Auto, Napa, Harbor Freight even Walmart should have an inexpensive multi-meter that would include a voltmeter. Usually you can pink one up at any of those locations I mentioned for about $5.

As far as the diagram goes, I would need to know what engine came in this.

Customer: replied 1 year ago.

Engine is a 3.6l. Would you suggest any of these voltmeter:

http://www.sears.com/search=voltmeter

Expert:  Mike S. replied 1 year ago.

And here is the wiring diagram.

Customer: replied 1 year ago.

Thank you. ***** know its a hassle but can you dumb down the instructions for me. From your diagram, is it correct that all the wires/connectors will be under the hood and exposed? Do I need to remove anything to access any of them?

Also, sorry, can you please explain how I will use the voltmeter to do the testing. I hope you can bare with me on the explanations. I would greatly appreciate it. Thank you.

Expert:  Mike S. replied 1 year ago.

Let's start with the battery. First take each battery terminal end one at a time in your hand and grab it and try to twist it as hard as you can in both directions. If it moves at all it is loose so tighten it up if it moves. This is the same way to check for loose connections also and you can start with following the ground cable to wherever it bolts to and twist it as well. Now if these 2 spots are tight, go back with the voltmeter and place the voltmeter on the DC volts scale about 20 should work. Now place the red positive test lead on the positive battery post and the negative test lead on the negative battery post and look at the voltmeter. It should read 12 volts. Now you are going to have to wait until the symptom of a no crank occurs before proceeding with any further tests or start twisting the electrical connections in the starting circuit trying to make the no crank occur now.

Let me know what you get so far, because you may have already found a loose connection.

Customer: replied 1 year ago.

Thank you, ***** ***** you know what i find out. ALSO, sorry stupid question, but is it correct that I am doing the initial tests with the engine OFF, correct?

Expert:  Mike S. replied 1 year ago.

Yes, exactly when NOT able to start or you would just have normal results.

Expert:  Mike S. replied 1 year ago.

I see this in an email this morning at 7:34am but it appears to be a little different from what you typed in at 4:30am, did you edit that post or something?

Here is what you said, "Thank you, I'll let you know what i find out. ALSO, sorry stupid question, but is it correct that I am doing the initial tests with the engine OFF, correct?"

Anyhow, to answer that as well, of course the engine will not be running cause you would only be testing when the starter will not crank, but you will be testing with the key on start, only when the starter isn't cranking, exactly like when you are having the symptoms of a no crank.

Customer: replied 1 year ago.

Sears only had this similar one, is it okay?

http://www.sears.com/northern-extech-electrical-test-kit-3-pc/p-SPM2203480914?prdNo=1&blockNo=1&blockType=G1

Expert:  Mike S. replied 1 year ago.

It's fine but a Fluke is expensive. If you plan on using it a lot yeah, but if you will probably never use it but this once, why not just go with a $5 multi-meter. I thought you had already purchased ne from before.

Customer: replied 1 year ago.

Ok, I think I checked the battery properly with the voltmeter. Reading was about 12.8.

Now what should I test? I have attached some pics of my engine area. The wires you see I tried pushing, tugging lightly, etc but nothing I was doing caused my car to start.

In general, not sure if the problem is related to heat from the engine. Maybe causing a wire or connection to slightly separate, then after the engine cools down a bit, the connection comes back together??

Expert:  Mike S. replied 1 year ago.

Does the starter crank over right now?

Customer: replied 1 year ago.

no, when it doesn't start it doesn't crank, no clicking, nothing. Here is a really short video I had posted about what it does. Sorry it is so short, I couldn't get my phone to upload a larger file.

Basically when I turn the key nothing happens, just the engine light stays on. I do hear a very slight 'whirring' sound that lasts for a few seconds but that is it.

https://www.youtube.com/watch?v=z4tU1eB0JiM&google_comment_id=z13ujjxi3neugd0zo04cd305sou5hpggckw0k&google_view_type=#gpluscomments

Expert:  Mike S. replied 1 year ago.

The whirring sound is mot likely the fuel pump but that is normal.

You are going to have to be ready to test when you turn the key to start and nothing happens. Since you don't even hear the starter solenoid click, I would start by testing for voltage to the starter relay when the key is on start. Remove the starter relay and test the prongs in the socket for voltage. One should be hot all the time nd then another hot when the key is on start.

Customer: replied 1 year ago.

Ok. To test the relay prongs in the socket, what do I set the voltmeter dial to? Then, do I stick both the black and red voltmeter prongs into each prong socket to test, or just either the red or black? And what should the volmeter be reading when I test each? Thanks so much

Expert:  Mike S. replied 1 year ago.

Set the voltmeter on dc volts around 15. Place the black (negative) test lead anywhere outside the relay onto a clean metal ground or on the battery negative post if it will reach that far. Place the red (positive) test lead on each of the prongs, one at a time and the reading should be 12 volts (battery voltage).

Customer: replied 1 year ago.

Sorry taking so long to test, of course now I am having a problem making my car not start. In the meantime, looking at the voltmeter I have:

http://www.sears.com/northern-extech-electrical-test-kit-3-pc/p-SPM2203480914?prdNo=1&blockNo=1&blockType=G1

should I set it to the vDC "20" setting in the upper left of the dial?

When we are done, I will gladly send you a good tip for all of your trouble and time spent with me on this. Thanks again.

Expert:  Mike S. replied 1 year ago.

Yeah, 20 vdc is right. Maybe you fixed the problem by wiggling around the connections.

Customer: replied 1 year ago.

I wish I did fix it, but when I was wiggling around the various connections, it was when the car was not starting and after the wiggling, the car did not start up. Still had to leave it for about another hour before it would start.

I'll let you know how the starter relay connector test goes once I get the car to not start again. It seems like I have to be driving it for about 1-1.5 hours at least before it will do that. Under an hour and it seems to still start up ok.

Expert:  Mike S. replied 1 year ago.

ok

Customer: replied 1 year ago.

Okay, I finally got my car to NOT start. I removed the Starter Relay and placed the dial on 20, and then placed the black prong on the battery's negative.

If you look down on the relay prong inserts there are 4. When I tested them, the top right tests just above 12 and the bottom left tests just above 12 as well. The top right prong insert tests at just above 3 and the bottom right reads 0. Is this the problem then? If so, how would I go about fixing it? Thanks!

Expert:  Mike S. replied 1 year ago.

The one that read 3 volts don't sound right.

You never said if you had the key on run, start or off.

Expert:  Mike S. replied 1 year ago.

Look back at that wiring diagram, this one. http://f01.justanswer.com.s3.amazonaws.com/heavy_chevy_396/43d8751c-4160-47f4-b47d-1442fc8b05fa_va200276.pdf

As you can see the starter fuse which is hot all the time feeds that starter relay, so remove that starter fuse and test the spots in the starter relay socket again, just to determine which is which, now this one will be dead. Then go ahead and hook that fuse back up. By the way this should be hot all the time.

Now pull the "htr vlv/cltch" fuse. Now which spot in the starter relay socket goes dead, just so we do know which is which. Both of these 2 spots should have the 12 volts though with the key on start. So now, that last one, which had the 3 volts. I don't believe that is right. Let me ask this, is it directly below either of those 2 that are hot and if so which one? It has to be either the spot that goes to the starter or the spot that goes to the ECM.

Expert:  Mike S. replied 1 year ago.

I suppose though since there is 3 volts there, you could check and see if there is 3 volts anywhere along the purple wire from that starter relay to the starter or if it is from that starter relay to the ECM along the yellow wire. You could possibly even check for voltage at pin 35 of connector 2 of the ECM nd if there is 3 volts there, the ECM is bad.

Customer: replied 1 year ago.

Ok, I'll try to test all of those. Just to be clear, when I do the testing where I:

-remove the starter fuse, then remove the starter relay and test the starter relay connections again, then later test after removing the "htr vlv/cltch" fuse, *is it correct that all of these tests need to be performed when the car will NOT start? Thanks.

Expert:  Mike S. replied 1 year ago.

First of all you are just trying to identify which connections or "prong inserts" as you called them are which. That is why you are removing the fuse, etc to see which one goes dead, telling you which fuse or whatnot feeds what prong insert. To better understand, just look at the wiring diagram.

The starter fuse is hot all the time so then again will be the spot in the relay socket be hot all the time. The htr vlv/cltch fuse is hot with the key on run and that ign relay is hot, so again will be the prong insert in that starter relay.

then once you determine which prong insert is what the other one that has the 3 volts, you have to figure out what that one goes to, because 3 volts is no good. Actually it should have either 0 or 12 volts and most likely 0 if the relay is out.

Customer: replied 1 year ago.

ok, not sure if I found which fuse/connection goes with the top right prong which reads about 3.

So when I take an initial reading of the 4 starter relay sockets=

top left 12

bottom left 12

top right 3

bottom right 0

When the starter fuse is removed, the starter relay sockets read=

top left 0

bottom left 12

top right 3

bottom right 0

When htr/vlv is taken out=

top left 12

bottom left 0

top right 3

bottom right 0

Expert:  Mike S. replied 1 year ago.

Were all these tests with the key off, on run or on start?

It appears to me from your results though that the starter fuse feeds the top left and the htr/vlv fuse the bottom left.

Now to figure out where that 3 volts is coming from. Check the purple wire at the starter solenoid and that at pin 35 of connector 2 of the ECM.

Customer: replied 1 year ago.

All tests done with the key in start(?; the position just before you turn on the engine).

OK, so somewhere under the fuse box around where the starter relay is there is a purple colored wire coming out of the bottom of the fuse box that goes to the starter?

When I get a chance, I will also try to locate and look at the starter itself. Someone who saw me checking at my car said that he had a chevy s-10 that had a wire coming from the starter itself that kept breaking/burning off and maybe there is a wire coming from the starter that may be broken off. I'll check anything at this point.

Expert:  Mike S. replied 1 year ago.

the key position right before start is run. It goes off, run and then start.

Customer: replied 1 year ago.

I have attached a pic of my fusebox. Are you talking about the thicker purple wire that is coming out of a cluster of wires in the lower right of the pic?

I did try to use the voltmeter at the base of a bunch of those wires. A lot of them were giving a reading about 12, but I could not seem to get a reading for the purple wire, as it kept reading 0.

As for the ECM, I had replaced it myself by buying a programmed one off of Ebay. But the problem still occurred so I switched back to the original ECM.

Expert:  Mike S. replied 1 year ago.

Yeah, that looks like the right gauge purple wire. One way to almost be sure is see if that has 12 volts when the key is turned to start and the starter does engage.

Now as far as the wire to the ecm goes, it might be shorted in between the relay and the ecm. It is not supposed to be any voltage, it is the wire that grounds the relay through the ecm.

Expert:  Mike S. replied 1 year ago.

Which relay in the fuse panel are you testing the socket of for the starter relay?

Customer: replied 1 year ago.

It's the one directly above the cluster of colored wires, to the right of the screw bolt. This is in the under hood fuse panel and not the fuse panel under the back seat.

Expert:  Mike S. replied 1 year ago.

Ok, that is the one I thought it was.

Now about that 3 volts, I am going to assume it's on the wire from that relay to the ecm, although I don't know for sure because the relay is in the socket. I did some research and I found a diagram on a relay that does show which prong feeds what, but I cannot tell unless you remove the relay and let me know what you are referring to as top left, bottom left etc and most importantly top right, since that has the 3 volts.

Customer: replied 1 year ago.

The starter relay in my car only has 4 prongs, not 5 like in your picture. Do you want me to send you a pic of it?

Expert:  Mike S. replied 1 year ago.

Yes, but a picture of the relay socket.

Customer: replied 1 year ago.

My bad, there are 5 prongs & sockets, but only 4 of the sockets have metal contacts inside. Here is the pic. So basically I do not consider the middle one on the right side/row when I describe the sockets as "top left, bottom right, etc".

Expert:  Mike S. replied 1 year ago.

Ok, any luck on testing the voltage along that yellow wire from that relay to the ecm?

Customer: replied 1 year ago.

Is it a yellow wire that is in the cluster of colored wires below the relay? I think there are two yellow colored wires there. Or should I start at the ecm and locate a yellow wire coming out of there? Would it be within the boundaries up wires in one of the two ecm connectors? Thanks

Expert:  Mike S. replied 1 year ago.

Start at the ecm.

Customer: replied 1 year ago.

I finally got a chance to look at the ecm (I attached a pic of the area). Not sure what I should be looking for/at. I just did a basic inspection of the immediate wires/connections but didn't see anything out of the ordinary. Do I need to look at the cluster of wires that are being plugged into the ecm?

*As a side note, not sure if it gives a hint to the problem, but when the car does not start, the length of time that it takes to be able to start again seems to be getting longer.

When this first appeared about 2-3 years ago, a handful of times a year it would take 2-4 tries to start the car.

Then about 8-12 months ago it would take about half an hour-45 minutes to be able to start the car. Then about 2 months ago it took about a 2 hour wait before I could start the car. Then last month about 3 hours. Yesterday's 'episode' took about 5 hours before I could start it. Not sure if that says anything to you about the problem.

Expert:  Mike S. replied 1 year ago.

It's connector c and pin 35 of the ecm where that yellow wire is. The thing is though the connectors have to be still hooked up when testing. Are those connectors marked? I wonder if someone makes a short jumper harness that you could plug in and have exposed wires where you could touch the tester lead to? Let me see if I can find something like that. If not, then somehow you will have to be able to touch the pointer lead to that yellow wire. I just don't want to tell you to poke the tester pointer through the insulation of the wire in order to touch the copper wire.

Expert:  Mike S. replied 1 year ago.

You know what, you said before, "Is it a yellow wire that is in the cluster of colored wires below the relay? I think there are two yellow colored wires there". Why not start there. Test both of those and see which has that 3 volts. Then if need be we will gain access to that yellow wire at the ecm but even a better method might be to just unhook that c2 connector at the ecm, pull the relay and use an ohmmeter in between the 2 ends of that yellow wire and see what the reading is. Although, since it is supposed to have 3 volts maybe not hooking an ohmmeter to a live circuit is a good idea right now, so go ahead and use the voltmeter first and see if it has that 3 volts with both ends disconnected and if it does, then it must be a short circuit in the yellow wire and it is touching a live wire. If it doesn't then plug back in the ecm connector and if the 3 volts comes back at that spot in the relay socket, then it must be coming from the ecm. I know you said you replaced it. Do you still have the old one?

Customer: replied 1 year ago.

I'll let you know when I can test those ecm wires. As for the ecm itself, it currently has the original installed. I had ordered a programmed one off eBay for about $400, but when that did not solve the problem I took it out to return and get a refund on it and put back the old one.

Expert:  Mike S. replied 1 year ago.

ok

Customer: replied 9 months ago.

sorry, still trying to figure out this problem. Someone I talked to suggested that the wire/connection that seems to be the problem area (from the volmeter readings above) and that it may be the wire going to the starter and that is activated by the chip in the key and maybe the problem is the chip key. Does that make sense? Should I try getting a new key cut from the dealer? Not sure since the problem happens while using both sets of keys and not just 1.