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Discussion Starter #1
My Honda Accord 2005 2.4L has a crank-no start problem. These are steps I have done on it.
1) tested spark and found none.
2) Fuel was OK, I heard fuel pump running and smelled gas when starting engine.
3)Replaced Crankshaft sensor.
4)Replaced ignition switch assembly dued to key issue
5)No key immobilizer issue.
6)No warning lights on dash board.
7) Scan engine and found no error codes.
Below is the descbription of the problem (I strongly believe so), with the key turned on I found
1) The ignition relay , R1, had 12 VDC at one end ( terminal 4, coil side) and also 12VDC at terminal 3, this implied that there was no path to ground. I also took R1 and bench tested it, it's fine. Terminal 3 is connected to PCM , terminal E7.
2) I removed R1, started engine, same problem, crank no-start
3) I did try to reset the PCM by it by disconnecting battery negative and removed F2,F4 and F7 which are engine management fuses and backup fuse.
History of car:
Like many of old Honda Accord cars, it had starting issues due to ignition switch. Sometimes it would buzz but won't start, key and key socket very worn out, one day it locked the steering wheel so I decided to replace it.
Due to Covid-19 my son was out of work for a few months. One day he had a job interview and the car did not run.
Questions:
1) Assumed that the PCM is the problem, why every thing else work and no light on dash board, no error codes.
2) There is open connection from the R1 to PCM. This is very unlikely to happen because no fuse burned.
3) Is there a way to test PCM without removing it from a car?
 

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Did you replace the electrical switch behind the ignition, or the key and mechanicals of the ignition? Not clear to me.


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The relay to the left of it is the ignition coil relay and the blue one below it is the fuel pump relay. Test those too.
 

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I bet you it's not the PCM.
  1. If you're not getting ground at the control side of the relay from the PCM, go directly to the PCM and pierce the wire to see if you have control side there. Reference the factory service manual to figure out which wire it is and match the color and pin number. You should see this go to ground; if not, you need to figure out if the PCM is getting the right signals -- if, for example, the PCM is not receiving the ignition switches properly, it will assume the key is not on.
  2. If the PCM goes to ground but not the relay, it indicates a rodent or some such has had lunch on your wire insulation or it has corroded etc.
  3. Identify what criteria the PCM is using to enable that relay through the service manual. This probably includes the ignition switch inputs. Find those wires (either within the steering column or go direct to their computer module side) and pierce them. Compare the switch outputs with the tables provided in the service manual.
  4. The only reason the computer would be bad is if you identify that all the powers and grounds are good, all the inputs are appropriate, but the computer is not properly driving that relay control to ground. The driver can fail (this is more common in like Chrysler vehicles).
  5. If all the inputs to the PCM look good, you can try replacing the relay with a switch and manually turn it on to see if the car will run.
My bet would be that the PCM is not receiving the correct set of ignition inputs from the switch to indicate the "run" position, or that you have a rodent chewed wire (I believe the Honda insulation is particularly tasty to rodents due to being made from a vegetable oil; this is especially likely to happen when the car is sitting for a period of time). There's usually a separate "start" wire, or perhaps the start wire bypasses the PCM and the starter relay will engage without the computer woken up due to no "run" signal.
 

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Describe exactly what the green key icon in the dash does when you put the key in, turn to on, then turn to start.

Do you have more than one key?


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Discussion Starter #8
Describe exactly what the green key icon in the dash does when you put the key in, turn to on, then turn to start.

Do you have more than one key?


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Thank you for helping me pinpoint the problem. Please see key sequences below
1) Inserted at off position
2) AC on, no lights on dashboard
3) On, the green key light was on for one second.
4) Start engine, crank won't start. RPM gauge shows about 300
5) Off, the green key light flashed 5 times.
No error codes on dashboard.
 

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Discussion Starter #9
Thank you for helping me pinpoint the problem. Please see key sequences below
1) Inserted at off position
2) AC on, no lights on dashboard
3) On, the green key light was on for one second.
4) Start engine, crank won't start. RPM gauge shows about 300
5) Off, the green key light flashed 5 times.
No error codes on dashboard.
I have two keys and they do the same
 

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Thank you for helping me pinpoint the problem. Please see key sequences below
1) Inserted at off position
2) AC on, no lights on dashboard
3) On, the green key light was on for one second.
4) Start engine, crank won't start. RPM gauge shows about 300
5) Off, the green key light flashed 5 times.
No error codes on dashboard.
If you have no codes, no security problem, and crank, you're missing:
  1. Spark: coil problem, control problem, power problem
  2. Fuel: injector pulse or fuel pump/pressure
  3. Compression/timing - could be failed timing belt. If this is the case you'll hear it crank without changing pitch and it will sound abnormal. All other compression problems usually result in a misfire not a no-start.
The easiest test from here is to open the airbox and spray starting fluid and see if it goes. You can also insert a spark tester or (carefully and holding from the end) pull one of the plug wires off the distributor and listen for spark while a friend cranks the car.

Also worth putting the battery on a charger.
 

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Discussion Starter #11
Did you replace the electrical switch behind the ignition, or the key and mechanicals of the ignition? Not clear to me.


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I did replace a complete set which consist of ignition switch anđ ignition key cylinder. I reuse the immobilizer.
 

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Discussion Starter #14
I bet you it's not the PCM.
  1. If you're not getting ground at the control side of the relay from the PCM, go directly to the PCM and pierce the wire to see if you have control side there. Reference the factory service manual to figure out which wire it is and match the color and pin number. You should see this go to ground; if not, you need to figure out if the PCM is getting the right signals -- if, for example, the PCM is not receiving the ignition switches properly, it will assume the key is not on.
  2. If the PCM goes to ground but not the relay, it indicates a rodent or some such has had lunch on your wire insulation or it has corroded etc.
  3. Identify what criteria the PCM is using to enable that relay through the service manual. This probably includes the ignition switch inputs. Find those wires (either within the steering column or go direct to their computer module side) and pierce them. Compare the switch outputs with the tables provided in the service manual.
  4. The only reason the computer would be bad is if you identify that all the powers and grounds are good, all the inputs are appropriate, but the computer is not properly driving that relay control to ground. The driver can fail (this is more common in like Chrysler vehicles).
  5. If all the inputs to the PCM look good, you can try replacing the relay with a switch and manually turn it on to see if the car will run.
My bet would be that the PCM is not receiving the correct set of ignition inputs from the switch to indicate the "run" position, or that you have a rodent chewed wire (I believe the Honda insulation is particularly tasty to rodents due to being made from a vegetable oil; this is especially likely to happen when the car is sitting for a period of time). There's usually a separate "start" wire, or perhaps the start wire bypasses the PCM and the starter relay will engage without the computer woken up due to no "run" signal.
I do like your bet and 100% agree that the either the conditions are not met for the PCM to ground the signal which enable the main relays or discontinuity. I will follow your advices accordingly and let you know. Thank you very much.
 

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Discussion Starter #15
If you have no codes, no security problem, and crank, you're missing:
  1. Spark: coil problem, control problem, power problem
  2. Fuel: injector pulse or fuel pump/pressure
  3. Compression/timing - could be failed timing belt. If this is the case you'll hear it crank without changing pitch and it will sound abnormal. All other compression problems usually result in a misfire not a no-start.
The easiest test from here is to open the airbox and spray starting fluid and see if it goes. You can also insert a spark tester or (carefully and holding from the end) pull one of the plug wires off the distributor and listen for spark while a friend cranks the car.

Also worth putting the battery on a charger.
1) It has no sparks. I checked it twice already. The CPM is not grounding the Main Relay therefore no sparks.
2) Because no sparks I did not check the fuel pressure however I did hear the fuel pump on for a few seconds when turned on AC and I smelled gas after I cranked the engined for a while. After cranking the engine for a while I also open the spark plug and it felt a bit damp and smell gas. Is it enough gas pressure? I don't know. Does weak gas pressure cause the CPM not providing ground to main relays ??
3) Again, due to the fact that I do not get sparks I do not check the timing. The engine crank evenly. No attempt to start.
 

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1) It has no sparks. I checked it twice already. The CPM is not grounding the Main Relay therefore no sparks.
2) Because no sparks I did not check the fuel pressure however I did hear the fuel pump on for a few seconds when turned on AC and I smelled gas after I cranked the engined for a while. After cranking the engine for a while I also open the spark plug and it felt a bit damp and smell gas. Is it enough gas pressure? I don't know. Does weak gas pressure cause the CPM not providing ground to main relays ??
3) Again, due to the fact that I do not get sparks I do not check the timing. The engine crank evenly. No attempt to start.
Did you check the control side of the relay at the module? I would:
  • Pierce the wire at the PCM (or whatever should be controlling the relay) and check to see if it changes properly. If it does, broken or corroded wire between relay and trigger.
  • Reference the factory service manual to deduce what inputs the computer requires to mean "run"
  • Check each of those wires at the PCM to make sure it's getting the necessary run signals.
  • Also check powers and grounds at the module to make sure it's getting power. This is best accomplished by loading the relevant power and ground feeds with a 3 amp headlight bulb with the connector unplugged to make sure the circuit can carry power (don't just test voltage as high impedance can still result in relatively normal looking voltage without load).
My bet given your issue is some problem with ignition switch or ignition switch wiring. Some scan tools will let you view a portion of this data which can be helpful for debugging ignition switch problems. If the ignition switch is the problem, you should be able to get the car to run by using a test light or jumper wire to apply power or ground to the malfunctioning lead on the ignition switch.
 

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Did you ever solve the problem and was it the pcm?.
I am having the same issue replaced the coil packs and spark plugs and still have no spark. I have fuel pressure and recently changed the battery.
 

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Did you ever solve the problem and was it the pcm?.
I am having the same issue replaced the coil packs and spark plugs and still have no spark. I have fuel pressure and recently changed the battery.
Did you also check the ignition switch inputs, the crank/cam position sensor, and the security system?

it’s almost never the computer.
 

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Not yet but before when it turned on the check engine light came on and it did spike revs on on idle. So I think I might try the cam/crank position sensor thanks l. Hopefully it's not the time belt.
 

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Not yet but before when it turned on the check engine light came on and it did spike revs on on idle. So I think I might try the cam/crank position sensor thanks l. Hopefully it's not the time belt.
Do you hear it compressing during the cranking? It will make a fairly distinctive irregular or flat pitched cranking noise if the belt snaps.

Also if it is thee belt you can buy refurbed heads online. Head for my '02 F23A1 is like $130 online.
 
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