Power Supply to CKP test

Power supply meets specification: B+

 

Power supply meets specification: B+....CKP Power Specification Voltage: 4.98V....Having determined that the problem lies in a signal circuit short to ground and a signal circuit short to battery.

It's great that your having a go at diagnosing this problem yourself but you've gone and gotten yourself confused because you didn't follow the proper test steps. You even had me confused there for a minute there until I spotted the mistake.

You did the test for the sensor power supply which passed.
The procedure says to follow the CKPS power test next if this test passed.

You did the CKPS power test next which also passed. So far so good.
It says "go to component inspection" next if this test passed....but you didn't.

Instead you went on to "signal circuit inspection", and this is where it all started to go wrong. Not totally your fault however.
There's a wee mistake in the Hyundai test procedure. They missed an important step when doing the wiring resistance checks. They forgot to instruct you to disconnect the PCM harness connector (step 2 below). The signal circuit wont have infinite resistance to ground or B+ while the PCM is still connected. But you didn't really even need to do these resistance tests because the previous voltage tests passed.

 

CKP Power Specification Voltage: 4.98V

CKP Power Specification Voltage: 4.98V
Test passed!

 

Signal Circuit Short-to-ground Check

Results: 1 on DMM

 

correction of earlier posted results

Results: 1 on DMM

There is a mistake in the results here...it should have been 0.2 ohms

 

Signal Circuit Short-to-battery Check

Result: 0.4 ohms on DMM

 

Signal Circuit Open Check

Results: 0.1 to 0.2 ohms
Continuity buzzer sounds

 

Ground Circuit Check

Results: 0.1 ohms on the DMM
Continuity buzzer sounds

 

Having determined that the problem lies in a signal circuit short to ground and a signal circuit short to battery.

how easy is it to take apart the wiring from the engine to the ECU?

Or should I sever the current wires and run new wires between CKP terminals 2 and the PCM on the one hand and between CKP terminal 3 and the ECU/EGR fuses?

 

I used my multimeter to run a test for shorts and found that the short was caused by the 30 amps power fuse in the engine compartment.

Once that fuse is removed, I get factory values from the CKP wiring, once that fuse is put back in the circuit, the values go out of specification.

I would appreciate some help with the schematics outlining the inputs and outputs and devices powered by this fuse so I can hunt down and fix the short

CC: wongpfh and autospark

Thanks

 

I used my multimeter to run a test for shorts and found that the short was caused by the 30 amps power fuse in the engine compartment.

Once that fuse is removed, I get factory values from the CKP wiring, once that fuse is put back in the circuit, the values go out of specification.

I would appreciate some help with the schematics outlining the inputs and outputs and devices powered by this fuse so I can hunt down and fix the short

CC: wongpfh and autospark

Thanks

Power Distribution/Junction Block/Starting System/MFI Control System Schematic Diagrams attached.

 

Component inspection just means remove the timing belt covers and inspect the sensor installation. You'd be checking the sensor is properly secured, the wiring hasn't been damaged (usually from chafing on the belt) and the vanes on the crank sprocket aren't damaged/bent. If you've just replaced the sensor I'm sure you will already have check all that.

So, where do we go from here? If you have a mutimeter that is capable of measuring frequency (or an oscilloscope) you can use that to confirm that the sensor is producing a signal. You'd need to back probe the red meter lead into the sensor signal terminal so you can take your measurement with the sensor connected to the harness. The black meter lead would connect to a good ground. Now crank the engine while monitoring the meter. Assuming the engine cranks at about 200RPM, and the sensor outputs 4 pulses per revolution of the crankshaft, you should get a frequency reading of approx 13Hz on the meter during crank....(200 * 4) / 60 = 13.3

 

No crank no start

The vehicle does not crank by itself when the key is put to the start position.

It only cranks if a cable is jumped between the battery positive terminal and the starter solenoid.

What is the implication of this to this diagnosis? Fix the starter circuit first?

 

The vehicle does not crank by itself when the key is put to the start position.

It only cranks if a cable is jumped between the battery positive terminal and the starter solenoid.

What is the implication of this to this diagnosis? Fix the starter circuit first?

So the engine doesn't even crank from the key?

Yes, fix the starter circuit first. For no other reason than it's a much simpler circuit than the engine management system.

The first thing to do is remove the START relay from the engine bay fusebox. Get a helper to hold the key in the START position while you measure the voltage on the 4 terminals of the relay socket. Make sure two of the terminals have a 12V supply.

If that checks out OK, do a bypass test on the relay circuit. Make sure the gearbox is in P/N, then use a short link wire to bridge the 30 & 87 terminals on the relay socket in the fusebox....see photo below for terminal locations. Does the engine crank when the relay is bypassed?

If the engine cranks and your terminal voltage tests were correct then either the relay is faulty (try swapping it) or the relay coil ground is open circuit.
If the engine doesn't crank there is a high resistance/break in the starter solenoid control wire between the fusebox and the starter motor.

START relay location

RELAY SOCKET
Terminal Locations

 

First of all, sorry for the long delay in getting back to you

Tested conducted: 2 of the START RELAY terminals have 12 volts power supply

Yes, the engine cranked when the relay was bypassed.

The former relay was bad, it was replaced with a relay that passed all the tests.

If I read you correctly, I should investigate the wiring from the relay terminals to the ground and from the relay terminal to the PCM and trans-axle switch if the relay is in good condition? that is, not open, if the relay is certified ok?

Because the wiring on the switch side of the START RELAY is ok!

 

If I read you correctly, I should investigate the wiring from the relay terminals to the ground and from the relay terminal to the PCM and trans-axle switch if the relay is in good condition? that is, not open, if the relay is certified ok?

Because the wiring on the switch side of the START RELAY is ok!

Yes, you confirmed two of the relay terminals had 12V when the key was held in the START position. Now look at the diagram below and you'll see where those two 12V reading came from, so you know those two circuit paths are good. But the relay doesn't switch on when you turn the key to crank. Since you know the circuit path from the ignition switch to the relay coil is good and you know the relay itself is good, the problem has to be a break in the relay coil ground. As you can see from the diagram, the PCM and the trans-axel switch aren't part of that circuit path, so all you really need to do is connect a ground to that terminal of the relay socket. It doesn't say on the diagram whether the ground is on the 85 or 86 terminal, but it should be the 85 terminal by convention.

BTW, just another little tip....notice on the diagram just below the relay it says "See Ground Distribution". That means the ground is shared with other circuits inside the fusebox, so you might want to check the grounds to those circuits too. That should give you an indication of where the fault lies. If the ground to the other circuits is OK, you know the fault is inside the fusebox and there isn't any need to check the wiring all the way back to the actual ground connection on the car body.

 

I'm quite surprised at that. I didn't think there was much chance of the wire breaking inside the fusebox since the wiring inside doesn't really move very much. Anyway, now that you know what the fault is there are two ways you can go about fixing it....the proper way or the quick and easy way.

The proper way involves unbolting the fusebox and opening it up to trace where the wire has broken inside and repairing the break. (will probably take 1 hour or so)

The quick & easy way is to just use a short length of thin wire to bridge the 85 terminal of the start relay socket to the 30 terminal of one of the fan relay sockets in the diagram above. Push the bare ends of the wire into the terminals of the relay sockets then refit the relays on top of the wire. (will probably take 5 minutes or so)

Either way should get the engine cranking. It's up to you to decide how much effort you think your car is worth.