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sprinkles08
sprinkles08, ASE Certified Technician
Category: Honda
Satisfied Customers: 22523
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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2002 Honda Odyssey 3.5L no spark? checked crank sensor, ok

Customer Question

2002 Honda Odyssey 3.5L no spark? checked crank sensor, ok checked timimg belt, ok so now what?
Submitted: 1 year ago.
Category: Honda
Expert:  Amedee replied 1 year ago.

Hello and welcome! My name is ***** ***** I can assist you with your question. Does the engine have fuel pressure when cranking it over? Do the ignition coils have power while cranking?

Customer: replied 1 year ago.
HI, I can hear the fuel pump running when i turn the key on, I looked for a port to hook a fuel pressure gauge to but I dont see one to make sure and I will have to check the coils tomorrow to see if they have power to them.
Expert:  Amedee replied 1 year ago.

Good morning! I do work all day today but will be on line later tonight. I will be looking forward to your reply!

Customer: replied 1 year ago.
OK thanks, ***** ***** there a port I can test the fuel pressure, like is it on the fuel rail?
Expert:  Amedee replied 1 year ago.

I dont believe there is a test port so you would have to tap into the fuel line to check pressure.

Customer: replied 1 year ago.
OK I have voltage at the coil when cranking.
Expert:  Amedee replied 1 year ago.

So I take it the PCM is not pulsing the coils to fire spark?

Customer: replied 1 year ago.
I should get a pulse on one of the other wires to the coil right? I gonna try a adapter to to do a fuel pressure test, what psi am I looking for here, 45-65? I do see on my snapon brick scanner shows the fuel pump relay off while cranking but I can hear the fuel pump running when I turn the key on.
Expert:  Amedee replied 1 year ago.

Yes, you should get a pulse when cranking at the ignition coils. This is how the computer pulses the Coke to fire spark. Yes the fuel pump relay should be activating while cranking. I will check the fuel pressure specs for you when I get home from work.

Expert:  Amedee replied 1 year ago.

Hello and sorry for the delay! Fuel pressure for this vehicle should be between 48 and 56 psi.

Expert:  Amedee replied 1 year ago.

If you are 100% sure that the valve timing and marks are correct, then my experience has been that this problem is caused by a bad PCM or a bad engine speed sensor. (crank, cam/TDC sensor). Now, if the crank sensor was replaced, it could be a wiring issue between the crank sensor and PCM or a wiring issue between the cam/TDC sensor and PCM. The best way to diagnose this condition is to scope the sensors using a lab scope while the engine is cranking over.

Customer: replied 1 year ago.
the timing marks are correct and The coils are getting a pulse signal on the pink wire which is usually the color from the PCM. I was not able to connect my fuel pressure gauge due to the threads being to long down on the line nut for my adapter to fit, I only have the snapon red brick scanner and it doesn't show the crank sensor.It does tell to check the ohm's on the crank sensor and that checked within limits. Is there a cam position sensor and if so where is it located?
Expert:  Amedee replied 1 year ago.

If the PCM is firing the ignition coils when cranking, then the engine should have spark. It is simple as that. Here are two pics of the TDC sensor.

Customer: replied 1 year ago.
this TDC sensor is located behind the front camshaft gear? should the ohms reading be the same across the terminals as the CKP? and which of these triggers the PCM or is it both?
Customer: replied 1 year ago.
also do you have the part number for the adapter for the fuel pressure gauge that you honda mech use?
Expert:  Amedee replied 1 year ago.

Hello and sorry for the delay! The adapter should be in the master fuel pressure kit. I dont know the number off the top of my head but you may be able to rent this from your local auto parts store. I do believe the PCM uses both the crank sensor and TDC sensor for the injector and coil timing

Customer: replied 1 year ago.
what should the ohms be across the TDC? I.m getting 2.02 and 1.94 on the 20K scale of the multimeter.
Expert:  Amedee replied 1 year ago.

Check the internal continuity of the sensors. Pins 1 Green wire and 2 Red wire are for cam sensor A, pins 3 Yellow wire and 4 Black wire are for sensor B. Specification is 1,850-2,450 ohms.

Expert:  Amedee replied 1 year ago.

.

Customer: replied 1 year ago.
That all checked out good, I rechecked for a pulse and i'm not getting a pulse at the coils. I did get good fuel pressure. Where is the PCM and which terminal is the pulse to the coils? or is there something else I should check first?
Expert:  Amedee replied 1 year ago.

The engine speed sensors need to be checked on a lab scope while cranking.

Customer: replied 1 year ago.
never heard of a lab scope, its this a dealer tool? and how is the speed sensor related to this no start condition?
Expert:  Amedee replied 1 year ago.

The computer needs to see the signal from the TDC sensor to start and run the engine. Any shop with a good diagnostic tech should have access to a lab scope.

Customer: replied 1 year ago.
ok I can understand that but you stated in the other post the speed sensor and now your saying the TDC sensor, shouldn't I be able to check the proper pin on the computer to see if i'm getting a signal instead of using a scope?
Expert:  Amedee replied 1 year ago.

The TDC is the engine speed sensor. YES you can check the signal of the TDC sensor right at the computer while cranking it over.

Customer: replied 1 year ago.
can you provide a pin out location picture and any other needed info to do this?
Expert:  Amedee replied 1 year ago.

YES, I will send it when I get home from work tonight

Customer: replied 1 year ago.
Amedee, maybe you should give me over to a different mechanic, we seem to be going in circles here and I need to get this van fixed for my friend. I don't have a lab scope and I think there should be a way to check the pin on the computer to check for signal both from and to the sensors. I should have already found the problem with help so this is why I suggest this.
Expert:  Amedee replied 1 year ago.

Ok, no problem. Good luck!

Expert:  sprinkles08 replied 1 year ago.

Hello and welcome to JustAnswer!

The first step in diagnosing the problem was to check for fault codes. Nearly any issue that will cause a lack of spark will set a code. Do you have as can tool or code reader?

Customer: replied 1 year ago.
No codes i have a snapon mt2500(red brick) I have fuel pressure just no spark, i have power to coil packs but no signal from PCM to coil packs. I have checked the ohms on the two sensors, crank and TDC sensors and they check good on ohms.
Expert:  sprinkles08 replied 1 year ago.

Checking sensor resistance won't tell you if a cam or crank sensor is capable of producing a signal. Can you see crank sensor RPM and cam/crank sync on the scan tool?

Customer: replied 1 year ago.
No it does not show for this van, i am hopeing to get the pin out location and check for signal there?
Expert:  sprinkles08 replied 1 year ago.

Does the tach climb when cranking the starter?

Customer: replied 1 year ago.
no it doesn't
Expert:  sprinkles08 replied 1 year ago.

The crank sensor isn't working then. Have the sensor ground and signal wire been tested?

Customer: replied 1 year ago.
no i just tested the ohms across the sensor i didnt check for ground or signal to it, i guess this is the next step right?
Expert:  sprinkles08 replied 1 year ago.

The sensor's ground should be tested as well as testing the signal wire for an open/high resistance or a short to power or ground.

Customer: replied 1 year ago.
with the key off the ground should be there or does the key have to be on? I know some PCM's use the ground to signal the sensor, is this the case with honda?
Expert:  sprinkles08 replied 1 year ago.

A sensor ground is always present.

Customer: replied 1 year ago.
Here are my findings 20K ohms scale key off, white wire 000 black wire 9.33 Key on white 0.51 black open. Voltage 2v scale, key on white .001 black .221 key off zero volts on both wires
Expert:  sprinkles08 replied 1 year ago.

Connect an incandescent test light's alligator clip to battery positive and take the probe end to the sensor ground terminal. Does it light?

Customer: replied 1 year ago.
ground on white wire
Expert:  sprinkles08 replied 1 year ago.

The sensor ground circuit is good then.

Customer: replied 1 year ago.
ok so what is the problem? I understand the ground is good. So what would you do next? You should be telling me if this checks ok then go here or if not, go here.
Expert:  sprinkles08 replied 1 year ago.

As I mentioned previously the signal wire needs to be tested for a short to power or ground, high resistance, and continuity needs to be tested between the sensor and ECM.

Customer: replied 1 year ago.
ok so which pin is the signal wire? do you have a pinout location for this and can you tell me its the black wire?
Expert:  sprinkles08 replied 1 year ago.

There are two wires at the sensor. The signal wire is opposite the ground that you already tested. The sensor ground is a white wire, signal is blue.

Customer: replied 1 year ago.
how do i test the signal wire? I know its got voltage when i turn the key on it was .221 volts
Expert:  sprinkles08 replied 1 year ago.

With the sensor unplugged you'll test it for a short to voltage, a short to ground, and you'll test it's continuity between the ECM and sensor. If it isn't shorted to voltage then move to checking it for a short to ground and then test continuity.

Customer: replied 1 year ago.
Haven't we already did these first two test? When I check the ground with the sensor unplugged by clipping the test light to the pos terminal of the battery and got a light when i touched it to the ground from the ECM then when I turned the key on and checked the signal wire from the ECM and got .221 volts, so now if i need to check continuity between the ECM and the plug for the sensor I need to know the pin location for this at the ECM? What am I missing here or is it I just don't understand your instructions? Its been two weeks now with you guys and I still don't know why it won't start. You got to know that most of both you guys answers just leave me hanging, you should be able to tell me to go to this if you get this result but you haven't. I'm just getting frustrated here. I changed to you because i had asked the first guy to send me a pin out on the ecm and he said he would that night and never did. Now I feel I'm right back at the same spot in the troubleshooting, I need the pin location for the signal wire to check continuity. I guess there is no way to just check the sensor to tell if its good or bad right?
Expert:  sprinkles08 replied 1 year ago.

Yes, the sensor can be tested with a labscope as we both mentioned but you don't have the equipment to test it properly.

As far as I am aware no testing of the signal wire has been done, the only thing tested was the sensor ground wire. The signal wire needs to be tested for a short to voltage, ground, and continuity needs to be checked. The signal wire goes to pin C8 at the ECM.

Customer: replied 1 year ago.
how about a diagram showing me where C8 is located, come on now. See this is what is frustrating me. You should know if I have to ask which pin you should know I need a diagram.
Expert:  sprinkles08 replied 1 year ago.

I can describe the pin location if necessary when I'm able to get back to my service information this evening, but I'm unable to post material directly from the service information due to copyright.

Expert:  sprinkles08 replied 1 year ago.

On the blue connector, facing the terminal end with the locating tabs facing up, pin 8 is third from the right in the top row.

Customer: replied 1 year ago.
What should the voltage be off the crank position sensor while cranking? I get .02 v at the highest reading.
Customer: replied 1 year ago.
blue plug unpluged from EMC pin 8 has no voltage with key on or cranking, it also has no short to ground
Expert:  sprinkles08 replied 1 year ago.

A labscope is needed to check the sensor's signal.

You'll need to check continuity of the wire from the sensor to the ECM.

Customer: replied 1 year ago.
ok so do both wires go from the sensor to the ECM if so, which go to what pin location? Also the sensors are hall effect so they produce a voltage ( most between .3 to 1 v) so again I ask you what should the voltage be off the sensor?
Expert:  sprinkles08 replied 1 year ago.

The sensor ground was tested and is ok.

The signal wire goes to pin C8.

A labscope is needed to test the sensor's signal.

Customer: replied 1 year ago.
I understand that is the best way to check them so the band width can be checked but they can also be checked for voltage. So is it you just don't know the voltage that these produce?
Expert:  sprinkles08 replied 1 year ago.

Voltage on the circuit is irrelevant and doesn't mean a signal is being produced. You can apply 3v, 5v, or even 12v or anything in between to the circuit but that isn't a signal. The signal is a square wave that can only be observed with a labscope. Being able to read a voltage on the signal circuit doesn't tell you anything about the sensor's signal.

Customer: replied 1 year ago.
Ok I got no continuity between the plug and the pin 8 so is there a fuse or a junction or is it just a solid wire between the two points?
Expert:  sprinkles08 replied 1 year ago.

There isn't a fuse because it's a sensor signal circuit rather than a power source. There's just a wire between the sensor and ECM.

Customer: replied 1 year ago.
the wire is broke somewhere?
Expert:  sprinkles08 replied 1 year ago.

Yes.

Customer: replied 1 year ago.
You stated earlier"There are two wires at the sensor. The signal wire is opposite the ground that you already tested. The sensor ground is a white wire, signal is blue" Pin 8 is a white with green trace, this is the wire I check. so its grounded through the ECM? Where does the blue wire go?
Expert:  sprinkles08 replied 1 year ago.

If the color doesn't match at the ECM connector and there is no continuity then you're most likely on the wrong wire. If you can upload a picture of the connector and wiring I can try to determine what's going on.

Customer: replied 1 year ago.
I can see the two wires at the sensor plug one is white with a green tracer and the other is blue, at the ECM the third from the right is white with green tracer
Customer: replied 1 year ago.
i';m uploading pics now
Customer: replied 1 year ago.
ok now i see the white at the sensor plug has no tracer, its solid white
Customer: replied 1 year ago.
I just checked all pins on the blue connector at the ECM and neither sensor plug wires have continuity
Expert:  sprinkles08 replied 1 year ago.

Do you have the VIN?

Customer: replied 1 year ago.
5FNRL18582B038035
Expert:  sprinkles08 replied 1 year ago.

Does the white wire next to the white/blue in the connector have continuity to the white wire at the sensor?

Customer: replied 1 year ago.
i tried both with all the pins and nothing
Customer: replied 1 year ago.
if you look close that white wire has a green trace next to the white/blue
Expert:  sprinkles08 replied 1 year ago.

How many connectors are on the module you're unplugging?

Customer: replied 1 year ago.
3 i think, there are two gray ones but i only checked the blue one
Expert:  sprinkles08 replied 1 year ago.

I'm showing the ECM to have three gray connectors, one black and one blue.

Customer: replied 1 year ago.
i'm sure it does, its just tucked under the center console by the firewall. So what now?
Expert:  sprinkles08 replied 1 year ago.

The wiring shows the same for every model year I looked at, let me see what I can come up with?

Customer: replied 1 year ago.
Any Idea yet?
Expert:  sprinkles08 replied 1 year ago.

What you're stating doesn't correlate to any Odyssey factory wiring diagram.

Can you set up the test light on the sensor ground wire, unplug each ECM connector one at a time and note which connector allows the light to go out?

Customer: replied 1 year ago.
i will do this now
Expert:  sprinkles08 replied 1 year ago.

Ok.

Customer: replied 1 year ago.
ok when I unplug the blue connector the light goes out, i have found the white wire at the blue connector it is the second from the left, top row and it has continuity
Customer: replied 1 year ago.
also the blue wire has continuity at the blue plug it is the third from the left top row
Expert:  sprinkles08 replied 1 year ago.

The wiring is good then. If there is no signal from the sensor then you have a bad sensor.

Customer: replied 1 year ago.
the only way to check it is lab scope, or should I do the same check on the TDC sensor first?
Expert:  sprinkles08 replied 1 year ago.

These sensors can be checked with a labscope or a scan tool.You can test the wiring to the other sensors if you'd like, you're already in the area and is something you can do without more sophisticated equipment.

Customer: replied 1 year ago.
do the crank sensors go out any more often than the TDC sensor?
Expert:  sprinkles08 replied 1 year ago.

The crank sensor would be most common.

Customer: replied 1 year ago.
if I want to check the TDC sensors would you have the correct pin location for these wires?
Expert:  sprinkles08 replied 1 year ago.

Sensor 1 is green and goes to pin 20, sensor 2 is yellow and goes to pin 29.

Customer: replied 1 year ago.
Ok so do you think its more likely to be the crank sensor, anyway to know which of the two have historical gone out first?
Expert:  sprinkles08 replied 1 year ago.

It's more likely to be the crank sensor.