No crank when hot

When hot no crank, no starter signal from start relay, relay test 83 tohms, power and ground at terminals in fuse box, Ecm shows crank request-yes in pid, purple/white from 26 in ecm connector c1 shows a voltage drop to .034 when the no crank occurs this voltage gradually increases to .470 at that voltage the car starts again (5-10 minutes) peak voltage is about 1 v during start up. Pretty sure this is a Ecm failure but the flow chart I have access to has no info on what the spec is for this wire.

My car has 125000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
The PCM supplies power to the purple/white wire which activates the starter relay. I would disconnect that wire from the PCM, mostly likely it would need to be cut somewhere it can be easily repaired or you will need to remove the wire from the relay connection. Once this is accomplished, I would use a jumper wire to supply power to the relay. This will test the entire system except the power coming from the PCM. Keep in mind, you want to do this when the car is hot and won’t crank. If the starter turns the motor over normally, I would definitely suspect the PCM.

In addition, I would check the voltage at the starter relay coming from the PCM when the car is cold. I would check voltage and not do a voltage drop. A voltage drop is not the appropriate test for this particular problem. I would then test the voltage at the relay coming from the PCM when the car is hot and won’t crank. If the PCM is indeed failing when hot, which is a common type of failure for a module, I would compare the difference in voltages. I would expect to see a difference of at least three or four volts. But most likely more.

Whenever I am potentially diagnosing a computer module, I do every test I can think of to be sure of my diagnosis. Modules do not fail as often as most believe and can be very expensive. I personally have only replaced a hand full in twenty years, with the exception of PCM’s in Chrysler minivans. If you need some help with these checks, have a certified technician, like one from YourMechanic, perform these tests and properly diagnose your starting issue.

Good luck!

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

The most common reasons a Saturn Aura won`t start are a dead battery, an alternator problem, or failed starter. Search our network of RepairPal Certified shops near you to speak with a technician about your issue.
The 2007 Saturn Aura fuel pump relay location is in the fusebox under the hood. To access the fusebox, pop the hood and look for a plastic black box along the right side of the engine compartment. Open it to reveal the fuses. The fuel pump relay is in slot 37, while the fuel pump fuse is in slot 27.
Bad Sensors

One common culprit for this problem is the crankshaft position sensor, which measures the position and speed of the crankshaft. The computer uses the information from this sensor to know when to fire the spark plugs. If the sensor isn`t working, the spark plugs won`t fire, keeping the engine from starting.

Problem Description. If the engine cranks but does not start, or starts and stalls, the fuses should be inspected, especially the power door locks fuse. The power door lock fuse provides power to a module that sends the Powertrain Control Module (PCM) the “OK to start” signal.
The fuel pump shut-off switch has a red reset button on top of it.
When the key is turned on, the powertrain control module (PCM) closes the fuel pump relay, which activates the fuel pump for about three seconds to pressurize the fuel injectors.
Location of Starter Relays

It`ll be under the hood, inside the large box with the black cover, in most autos. This is where a vehicle`s fuses and relays are mounted, and it`s also known as the fuse box. The box is normally mounted on the driver`s side of the vehicle.

Starting relay position

In most cars, it will be under the hood, in a large box with a black lid. This is where car fuses and relays are installed. It is also called a fuse box. This box is usually installed on the driver`s side of the vehicle.

your car fails to start: the engine`s computer uses the map sensor to gauge atmospheric pressure before the engine is started. a false reading could cause too much or too little fuel to be delivered to the engine. both conditions could keep it from firing up.
In that day, a cranking, no-start condition could easily be diagnosed by testing the available spark at the spark plug. If there was no spark, we touched a test light to the coil negative terminal to determine if the distributor contact points were switching the coil on/off (see Photo 1).
Broken or Damaged Ignition

If your headlights can turn on, but your car won`t crank, that means that your battery is charged, but either the starter or ignition is the problem. If the starter or ignition is the problem, a starter engine can be jumped by using a charged battery.

If the relay fails it will cut off power to fuel pump and ignition system, which will result in a no power, and therefore no start condition. You may find that turning the key may power on the accessories, and may even crank the engine.
Another symptom of a faulty fuel pump relay is an engine that does not start. If the fuel pump relay fails the fuel pump will be left without power. The engine may still crank when the key is turned, however it will not be able to start due to lack of fuel.
Easy…… use a push button as a start with one of your relay contacts(or an aux relay) as a hold-in across the start button. Your float switch then becomes a series stop switch. The latter would of course have to be normally closed during normal operation.
The Fuel Pump Driver Module controls the voltage delivered to a vehicle`s fuel pump. By controlling the voltage, the module maintains optimal fuel pressure and fuel delivery to the engine throughout its full operating range.
The fuel tank pressure sensor is part of the fuel pump assembly and is mounted on top of the tank or inside the tank. It`s part of the evaporative emissions system (commonly referred to as “EVAP”) and reads pressure in the fuel system to detect evaporative leaks, such as a loose or faulty gas cap.
A failed PCM or TCM can cause the car to get stuck in gear, which can be a serious safety issue. It can also lead to costly transmission damage.
Why won`t my car start but the battery is good? If your car won`t start but the battery is good, the most common cause is a faulty starter – though it could also be to do with your fuel. You may have insufficient fuel to get the car going.
But a faulty solenoid that fails to make adequate electrical contact inside can also produce this tell-tale sound causing the battery to have low voltage unable to provide enough power to start your engine.
The starter solenoid is an electromagnetic switch that engages the starter motor. How can I tell if my starter solenoid is bad? If you`re having trouble cranking the engine over but the battery is charged, or if your starter won`t disengage after starting the engine, it`s likely a starter solenoid issue.
The starter solenoid is sometimes called the starter relay, but many cars reserve that name for a separate relay which supplies power to the starter solenoid. In these cases, the ignition switch energizes the starter relay, which energizes the starter solenoid, which energizes the starter motor.
Why won`t my car start but I have power? If you attempt to start up your car but the engine won`t turn over and the dashboard lights up, then you most likely have an issue with your battery. You could have a damaged or corroded battery terminal, which is stopping the engine from starting up when you fully turn the key.
The most common reason cars don`t start is a dead or faulty battery. Even though most cars run on gasoline, they all require electrical power to function. The starter that cranks your engine to start requires an electrical signal to fire. If something`s wrong with your battery, your car engine won`t turn over.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

its cranks slow, sometimes it cranks fine and other times i have to crank it twice, it happens randomly
ANSWER : A slow cranking condition is caused by not getting enough power to the starter. Since you replaced the starter then you may have a weak or borderline bad battery. One of your cables may be bad causing the slow crank condition.

If the battery is weak then you may get the problem one time and a sudden burst the next. If you battery is more than a couple years old I’d suggest having it load tested to see if it is bad or if is a cable problem.

Do not rule out the starter even if the problem was fixed for a while after the starter was replaced. I’d suggest getting your vehicle inspected by a qualified professional, such as one from YourMechanic, to diagnose your starting issue and repair it as necessary. Good luck.

Read Full Q/A … : No crank when hot

Died,then wouldn’t crank for a few min then cranked and drive but cut out once in the way back home.
ANSWER : This may sound like a dumb question, but when was the last time you put gas in it? It may be possible that the fuel gauge sending unit is failing and giving you a false reading. It is also possible that you have an electrical concern. If you have the Check Engine Light on, it will indicate that there is a diagnostic trouble code stored. If so, have the vehicle scanned for the codes, and that may help identify the system or component that requires further testing. A certified technician, like one from YourMechanic, will be able to diagnose these trouble codes and determine the exact cause of your concern.

Read Full Q/A … : No crank when hot

While driving defroster set to hot blows hot air as it should, while idling it is blowing cold air.
ANSWER : First, the coolant level should be checked to make sure the radiator is full. While the overflow tank may be full, the radiator cap must be taken off to check the level inside the radiator. If you find the level is very low, you have a coolant leak that must be fixed. If coolant levels are normal, an engine thermostat or heater control problem may be what you’re experiencing. Consider hiring an experienced technician like one from YourMechanic who can come out and take a closer look at your lack of heat concern to offer a more personal diagnosis.

Read Full Q/A … : No crank when hot

I have been having cold drinks every morning I cranked it up a few times and then I guess when it gets heated up it cranks but now
ANSWER : Hi there. Sometimes when it gets cold outside, the fuel system will loose pressure and cause a cold starting issue. Another cold weather issue is sometimes caused by a cold start injector. This part is located on the cold air intake, which is found on the intake manifold. It is a fuel injector that is controlled electronically. The cold start injector works only when the engine has a cold start, or when the engine’s temperature is below a certain point. When this happens, a computer tells the injector to inject more fuel into the mixture that goes through the cylinders to the engine. You might want to have a professional mobile mechanic come to your location and complete a car is hard to start inspection.

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Hey i have a 2000 focus and the heat blows hot but it only stays hot for about 1 minute then it goes cold. I have to wait 5 minute
ANSWER : Hi There,
If your heat blows warm and then cold in addition to the engine overheating, this may very well be a thermostat issue. This may also be an issue of air being trapped in the radiator or heater core. This causes this type of cycling effect with hot and then cold air being blown into the cab of the vehicle. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your vehicle.

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My air is blowing cold-hot-cold-hot-cold-hot…
ANSWER : It is possible that you have a leak in the AC system. There are pressure switches that will turn off the compressor if the pressure is too high or too low. The low refrigerant level could cause the AC compressor to cycle on and off. If you would like to have this done, a certified technician from YourMechanic can come to your car’s location to diagnose the AC system and make the correct repair.

Read Full Q/A … : No crank when hot

Car won’t crank when it’s cold and now won’t start at all
ANSWER : Hi there:

Usually this issue is cased by low cranking amps inside the battery. If you’ve recently had the battery replaced, it’s possible that an electrical component that makes up the charging system might be damaged or faulty. It’s also quite possible that the main electrical relay or the starter relay is giving you fits. To know for certain what the exact issue might be on your 1989 Toyota Camry, you should have a professional mobile mechanic complete a car is hard to start inspection, so they can pinpoint the source of your issues and recommend the right repairs.

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My 05 Chrysler300 5.7 hemi ran hot because my belt was loose and cranks but won’t start
ANSWER : If your belt isn’t tight like it should be, your alternator probably isn’t charging your battery properly. If it continues after you replace your belt, you may want to look into replacing your alternator. If your belt isn’t tight even without driving, you may want to replace your tensioner pulley.

Your belt not being tight could possibly be the cause of the problems that are occurring. The first thing you will want to replace is the tensioner pulley and possibly the belt if there is any damage done. I recommend having a service technician, such as one from YourMechanic, replace the tensioner pulley and perform an inspection to find out if your alternator is performing the way it should.

Read Full Q/A … : No crank when hot