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Jared D
Jared D, ASE Certified Technician
Category: Honda
Satisfied Customers: 1914
Experience:  Shop Supervisor at County Fleet
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My car has check engine light and codes are p1298, p0135,

Customer Question

My car has check engine light and codes are p1298, p0135, and p0141
Submitted: 2 years ago.
Category: Honda
Expert:  Jared D replied 2 years ago.

Check the wire harness under the intake manifold. The wire harness by the brace, or bottom of the intake manifold, will rub and short out the Black/Yellow wire and cause the fuse #15 to blow and set all the codes.

There is also a factory TSB on this problem. If the wire harness is OK, try unplugging the junction connector and power each circuit separately, and see what circuit the short is located on.

If no problem is found there, verify that the Bypass Solenoid (BS) for the Evaporative Emission Control System (EVAP) is not shorted. If that is the problem, the fuse will only blow when the Engine Control Module (ECM) runs an evaporative test and the solenoid may damage the ECM.

If it is a Civic EX look for the rear O2 sensor wires shorted to the exhaust shield.

Customer: replied 2 years ago.
I checked harness and it looks good I checked the fuse It's not blown I check the o2 harness it looks good also
Expert:  Jared D replied 2 years ago.

The harness under the intake manifold support bracket wasn't rubbed through? That's a very common problem with this engine. Let me see if there is anything else it could be.

Customer: replied 2 years ago.
I even changed a different ecu and a alternator because lights dimme out and speedometer bounces up and down
Customer: replied 2 years ago.
The harness didn't looked rubbed at all
Expert:  Jared D replied 2 years ago.

According to the wiring diagram a bad transmission ground cable could also cause the same codes to set.

Customer: replied 2 years ago.
I double checked my grounds also
Expert:  Jared D replied 2 years ago.

I take it you've seen this TSB?

From what you describe, there has to be a short to ground somewhere.

Expert:  Jared D replied 2 years ago.

Here is a solution from another honda mechanic with the same problem:

P1298, P0135 and P01334. Found blown #15 fuse but no harness issues. Found about 30 ohms at the Bypass Solenoid by the fuel tank. Left unplugged and codes did not return but failed Evap. flow as expected. Replaced Bypass Solenoid.

Could you try to unplug the bypass solenoid and drive it a little to see if the problem persists?

Customer: replied 2 years ago.
Yea I seen the tsb but the weird part its not blowing up the fuse checked and I checked all the grounds
Customer: replied 2 years ago.
I'll try it
Expert:  Jared D replied 2 years ago.

What if you clear the codes and switch the o2 sensor harness connections? Then if the B1S2 O2 sensor turns off, and the code for the lower sensor is set, then replace the upper sensor because that is your problem. Just make sure to swap the connectors back to normal afterwards.

Customer: replied 2 years ago.
Yea I try that already but didn't work either
Expert:  Jared D replied 2 years ago.

In my opinion, the only thing left to check is the bypass solenoid...as long as there are no shorts to ground.

Customer: replied 2 years ago.
Do I have take the gas tank off?
Expert:  Jared D replied 2 years ago.

No. I'm pretty sure you can get to it without pulling the tank. It's on top of the charcoal canister next to the tank.

Customer: replied 2 years ago.
I tried it did the same thing
Expert:  Jared D replied 2 years ago.

I don't know what in the world is going on. You have checked every part of this system in relation to those three codes. I still think there must be a short somewhere. Can you disconnect the harness and check each wire for resistance between the terminal and ground?

Customer: replied 2 years ago.
How do I do that
Customer: replied 2 years ago.
How I measure the resistance
Customer: replied 2 years ago.
Another thing also alternator doesn't charge but I replaced it twice
Expert:  Jared D replied 2 years ago.

Set your volt meter to ohms, then probe each pin on this connector and then touch the other probe to a good chassis ground. If you see a high number or OL then that's good It means that circuit is not grounded. If you see a fairly low number 20 ohms or below, then that circuit is shorted to ground. Use this connector view to determine which pin is showing shorted.

Expert:  Jared D replied 2 years ago.

Here is how to diagnose the alternator. Pay close attention to the last step about the ground. That could be causing your other issues too.

1. Verify that the Black/Yellow wire at the alternator has battery voltage with the key on, and verify that the charge light works if the key is turned on. The voltage regulator needs to ground the White/Blue wire to illuminate the charge light.

2. The Electronic Load Detector (ELD) circuit also has control of the alternator. To test the ELD circuit, backprobe the White/Green wire with a voltmeter. If the Engine Control Module (ECM) is signaled by the ELD that the alternator should charge, it will not ground that circuit. When there is no ground and voltage on the wire, the alternator should charge. If the wire at the alternator tests good, then the alternator is faulty.

3. Verify the alternator case to engine block to body has a good ground.

Customer: replied 2 years ago.
Battery light doesn't come on
Expert:  Jared D replied 2 years ago.

So then you have no ground at the voltage regulator. Can you use your multi-meter on ohms between the alternator case and the negative terminal on the battery? Let me know what reading you get.

I'm assuming you have a multi-meter. Sorry. Do you?

Customer: replied 2 years ago.
Yea I do
Customer: replied 2 years ago.
Do I read it with 20k
Expert:  Jared D replied 2 years ago.

What do you get if you switch it over to DC volts and put the positive lead on the positive battery terminal and the negative lead on the alternator case?

Customer: replied 2 years ago.
11.8
Customer: replied 2 years ago.
the other way around I get 0.9
Expert:  Jared D replied 2 years ago.

Did you check for 12v at the black/yellow wire?

Were you able to test the ELD circuit as described?

Customer: replied 2 years ago.
I only 1.20 on blk wire using dc 20v on multi meter
Expert:  Jared D replied 2 years ago.

That actually sounds correct. You are probably seeing 12v rather than 1.2v because of the setting on the meter.

Customer: replied 2 years ago.
What else you think it could be?
Customer: replied 2 years ago.
How would I check eld circuit
Expert:  Jared D replied 2 years ago.

Backprobe the White/Green wire with a voltmeter. If the Engine Control Module (ECM) is signaled by the ELD that the alternator should charge, it will not ground that circuit. When there is no ground and voltage on the wire, the alternator should charge. If the wire at the alternator tests good, then the alternator is faulty.

Customer: replied 2 years ago.
Alternator Is brand new
Expert:  Jared D replied 2 years ago.

I know, but it doesn't mean it isn't faulty. I have a fleet of police cars and we replace two or three alternators per week. 1 in 20 or so come faulty right out of the box. That is using brand new factory brand alternators. The re-manufactured, aftermarket brand alternators have a much greater fail rate.

Customer: replied 2 years ago.
I replaced it 3 times
Expert:  Jared D replied 2 years ago.

Can you run a temporary ground wire straight from the negative terminal on the battery to the engine block?

And also maybe a ground wire straight from the negative terminal to the alternator?

Clear all of the codes and then see what com

Expert:  Jared D replied 2 years ago.

Can you run a temporary ground wire straight from the negative terminal on the battery to the engine block?

And also maybe a ground wire straight from the negative terminal to the alternator?

Clear all of the codes and then see what com

Expert:  Jared D replied 2 years ago.

Can you run a temporary ground wire straight from the negative terminal on the battery to the engine block?

And also maybe a ground wire straight from the negative terminal to the alternator?

Clear all of the codes and then see what com

Customer: replied 2 years ago.
Same codes
Expert:  Jared D replied 2 years ago.

Sorry that posted 3 times. I don't know if my internet was freaking out, or the just answer site....

Anyhow, were you able to check each of those terminals in the connector for short to ground?

Customer: replied 2 years ago.
Yea everything seems right
Expert:  Jared D replied 2 years ago.

I guess the only thing left would be the PCM. If everything else tests ok then it must be the computer.

Customer: replied 2 years ago.
I replaced it already
Customer: replied 2 years ago.
What I noticed to I turn on the key and the little battery in the cluster turned on and cleared the codes I lt ran fine no vss problems alternator was charging and headlights weren't dime the the check engine came on and it the little battery wouldn't show anymore
Expert:  Jared D replied 2 years ago.

So it's fixed now?

Expert:  Jared D replied 2 years ago.

I just wanted to see if you needed any additional information. Also, I would appreciate a positive rating if I have been of any assistance. Thanks!