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The 12V battery was replaced in May of this year so it's fairly new.
One less thing to check then. There have been many with very odd issues with CR-Zs and it usually ended up being the under hood battery. Quickest cheapest fix if it had not been replaced.

Since it is regenerative braking only that is affected, what sensors , switches or fuses are involved with the brakes ( I think rear wheels only) only for regenerative braking?
 

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I'm sure the brake pedal switch is the main activation for this. Of course the engine must be in gear and the wheels turning. As his IMA seems to working as far as assistance and normal charging goes, the only sensors that might be involved are the ABS pressure sensors, and the engine manifold pressure sensor. (vacuum will be max when off the gas).
If its not as simple as a faulty brake pedal switch, then a full diagnostics is recommended, not just of the IMA, but of the engine and ABS/VSS.
 

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Ironically, this morning when I started up, the IMA light came on, with a "check IMA system" message.
It was 7C and due to short daily journeys at less than 40mph, plus driver's seat heating on, I guessed that the 12v battery was low. The IMA was still working - assistance and charging as normal and after a 15miles and a restart, no warning light or message. (new high quality battery in August)
I will have to drive the long way to the post office and with more verve!
 

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Hi!
The 6MT in my 2014 CR-Z needed to be overhauled (a bolt on part of the shifter assembly inside the gearbox broke, and the nut, lockwasher & spring fell into the spinning gears). After I got the car back, I noticed that regenerative braking wasn't working. The CHRG indicator very briefly jumps to 2-3 bars when I take my foot off the accelerator and quickly goes back to no bars. No CHRG bars appear at all when I hit the brakes. The IMA battery does charge when I drive, but even a small amount of stop-and-go traffic will drain the IMA battery down to 2-3 bars on the IMA Battery Charge Level Indicator. Usually I can keep that indicator at 6-7 bars with normal city traffic.

I took the car in to the dealer, described the problem to them, they ran a diagnostic and said the IMA battery charging was behaving normally. Which is true; the engine does charge the IMA battery. But I'm guessing the diagnostic doesn't cover charging from regenerative braking? My dealer didn't charge me for the diagnostic so I'm happy about that, but I would like to have the IMA available like it was in the past, especially when I need a bit more hustle to navigate traffic on a busy day.

I wanted to do some research before I take the car to another dealer. I'm thinking about buying the service manual to see if it has any useful information or hints, but I thought I would ask here first. Thanks!
Have you tried higher rpm and backing off the throttle?
The brake switch is a reasonable answer to your issue but as you describe it, it goes to zero bars regeneration after a second when you lift off the throttle.

It could be the simpler issues but i can't see how a brake pedal switch is at fault if it won't charge when no pressure is applied to the pedal if you get me?

Was the transmission rebuilt or changed because the final drive is different in the 13 onwards cars, the ecu is programmed to take engine vs wheel speed into account when regenerating

If you have a 10-12 fd or gearset then your '14 ecu won't be receiving the data it should or is programmed to receive and regen braking and regen when lifting off could be turned off.

2012 Final Drive: 4.11
2013 Final Drive: 4.29

Roughly a 4.2% difference.

If the 12v battery and clutch switch are a dead end try find out what was replaced in your transmission. If the fr which is usually the layshaft on the box got damaged when it was rebuilt, and they used a 4.11 FD then this could be your issue
 

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It must be charging when he's driving or he'd have an IMA warning light and no assistance.
Its just the 'extra' charging when braking that doesn't seem to be working.

If the IMA battery is actually well charged, you don't see any charging bars on the charging meter. When I get my IMA battery to 100% by coasting down a long hill, all I see are a couple of green bars briefly when I lift off and no more when I brake - as you would expect with a full battery.

The acid test is to drive the car hard in Sport to drain the IMA and see if more green bars appear on the over run and when braking.
 

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Charging while driving wouldn't write off the problem of regen as they tend to charge 1 green bar on the motorway if you are on the most imperceptible of declines. The regen is the most important aspect here and of a hybrid arguably because using engine power to generate battery power while driving is the reverse of a hybrids primary purpose, instead of recouping lost energy from braking and acceleration your using more to recharge.

Something fucky is going on.

Considering it started after a rebuilt box and the difference in the gearing between models, if enough damage was done to warrant a final drive, which is the layshaft in an fwd box and the crown wheel then its not outside the realm of possibility that the lack of regen is fd related.

Engine rpm is measured off the cam sensor, you also have the sensor on the diff for speed and the abs sensors on the wheels.

I'm sure honda has a discrepancy built in for the wheel speed sensor because multiple wheels sizes were available from factory but a difference in the vss and the cam sensor vs what it is anticipating might make the ecu think a clutch slip is happening.

I. E. Higher engine rpm vs wheel speed/vss sensor.

Could be something silly but checking the part numbers of what was used in the overhaul vs the correct fd part number will answer the q quickly
 

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Discussion Starter #27
The service tech at the repair shop said the transmission was making noises after the shifter was repaired and they didn't find the missing pieces of the original bolt, so the assumption was they fell into the spinning gears (the car was in motion and in gear at the time the bolt broke). I was told either a full rebuild or a replacement transmission was the best way to go. I chose the full rebuild because that was the middle ground at $5700. A factory new transmission was around $8900 and a used transmission was around $1200 but only had a 90 day warranty. Another shop did the rebuild and there wasn't much detailed documentation about the work that was done from the repair shop and none from the shop that did the rebuild.

I'm sure honda has a discrepancy built in for the wheel speed sensor because multiple wheels sizes were available from factory but a difference in the vss and the cam sensor vs what it is anticipating might make the ecu think a clutch slip is happening.

I. E. Higher engine rpm vs wheel speed/vss sensor.

Could be something silly but checking the part numbers of what was used in the overhaul vs the correct fd part number will answer the q quickly
I did notice the gearing has changed. The car would go 70 MPH on a level road at 3000 RPM in 6th gear and now it's 75 MPH at the same RPM and gear. That's a 7.14% difference.
I'm trying to find info on the relevant ECU in the 2011-2012 Service Manual PDF to understand more. Can someone point me at page numbers? Thanks!
 

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Yeah it looks like you have a 4.11 fd.
It think a question re final drives was asked in a hondata forum and the programming for the regen stuff is in the ima ecu so you cannot change the gearing via a reflash.

I think your only option is the correct final drive 😢
 

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Why will changing the final drive affect the non regen charging?
The IMA ecu is behaving as if it doesn't know the brake pedal had been pressed.
Any sensor problem would have caused warning lights and DTCs.
But is your reversing/backup light working? (been reconnected during the transmission change?
 

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Why will changing the final drive affect the non regen charging?

It doesn't.

Non regen charging isn't the issue.
He isn't regenerating at all when he lifts the throttle, he describes the charge bar coming on and off really quick. The brake pedal is irrelevant if he isn't using it.
 

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Might be worth running the gauges' self diagnostic:

Entering the Self-Diagnostic Function (Manual method)
1. Push and hold the SELECT/RESET knob.
2. Turn the combination light switch ON.
3. Turn the ignition switch to ON (II).
4. Within 2—5 sec. turn the combination light switch OFF, then ON and OFF again.
5. Within 5 sec., release the SELECT/RESET knob, and then repeatedly push and release the knob three times.
NOTE:
• While in the self-diagnostic mode, the dashlights brightness controller operates normally.
• While in the self-diagnostic mode, the SELECT/RESET knob is used to start the Beeper Drive Circuit Test and the
Gauge Drive Circuit Check.
 

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The issue is mechanical.
All the diagnostics in the world won't fix it or provide a solution.

Nor will searching the service manual for 10-12 models hoping for a solution in the ecu section.

Firstly it is a different ecu with different programming, secondly the regen programming is part of the ima computer.

Hondata/kpro software cannot be used to correct gearing in the ima computer or even view the programming according to their respective forums.

If indeed, and it sounds like it is based off the speed vs rpm discrepancy, the problem is the final drive, the solution is purely mechanical in nature and that cold hard billet of steel cannot be diagnosed or sorted with electronics, it will have to be changed.
 

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Discussion Starter #33 (Edited)
Got it! I was just looking to get some background information so I can better explain the problem to the service rep/tech at the dealer. I'm anticipating that they won't see the connection between the change in the transmission gearing and the regeneration logic/programming in the ECU and the IMA controller.
If I could point to relevant information in official Honda documentation, I think that would carry more weight than saying I got the information from an Internet forum.

Also, with the goal of helping the technician in mind, if the ECU and/or IMA controller is not allowing regenerative charging to happen, is that condition flagged and can be detected by diagnostic gear?
 

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If the IMA is not charging I would expect a fault code, so a full diagnostics is the first step because if it was caused by a discrepancy between rpm and wheel speed, then there would be one.
 

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Discussion Starter #35
I'm hoping there is a fault code too, because it makes sense to me generate one. I specifically told the dealer service rep that regenerative braking was not working and I see that problem description in their paperwork. So I was somewhat surprised when I was told they didn't find any problems. I'm pretty sure I can't go talk to the technician(s) while they working on my car because of safety reasons (and related liability insurance policies), so I figure I will have to present the problem in a more detailed manner to the service rep that can be then passed along to the technician.

I do remember the service rep telling me after they checked my car that the IMA battery is charging and that the technician verified it with a test drive. That is partly true, the engine does charge the IMA battery. But I don't know if the service rep or the technician are familiar with how regenerative charging is triggered in a CR-Z. I assume it's similar to the Insight but I've never driven an Insight. So I'm hoping to go back with some specific items for them to check. With the pandemic, I don't think I can ask them to accompany me on a test drive so I can show the technician what is not happening when I take my foot off the accelerator and/or when I use the brakes.
 

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Did they check all the relevant ecus for DTCs?
I don't know anything about Honda's HDS diagnostics, but on most vehicles, once connected to the vehicle, a list of ecus present is displayed, you choose one of interest and then check it for DTCs. You have to do this for every ecu that's relevant to the symptoms. So did they check the engine, the IMA, A/C and the ABS/VSA, or just the IMA or just the engine?
If non have any DTCs, the next step is an actuator test - all 3 pedal sensors, gearbox neutral and reverse gear switches, ABS pressure sensor/switches etc. Regardless of whether it is the final drive change that is the root cause, there ought to be a diagnosable reason why the IMA is not charging correctly.

However it is possible that Honda, never anticipating anyone would change the final drive for a different ratio, have not programmed a DTC to show this as a fault, in which case you would only find out by reverting to the original ratio.

Can you get a family member to video you driving and record what the IMA display is doing which you can show to the service manager or upload to Youtube?
 

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Got it! I was just looking to get some background information so I can better explain the problem to the service rep/tech at the dealer. I'm anticipating that they won't see the connection between the change in the transmission gearing and the regeneration logic/programming in the ECU and the IMA controller.
If I could point to relevant information in official Honda documentation, I think that would carry more weight than saying I got the information from an Internet forum.

Also, with the goal of helping the technician in mind, if the ECU and/or IMA controller is not allowing regenerative charging to happen, is that condition flagged and can be detected by diagnostic gear?
If you have no code you won't have a code. This is purely mechanical. The ecu and diagnostics only tell you about sensor issues or parts that are connected to the ecu through the wiring loom and report data back to the ecu.

The final drive/gearset isn't electronic save for the vss sensor but that is taking a reading off the diff. So if the vss is still reporting road speed it won't set off a code.

Best bet is go onto honda parts now and screen print the different part numbers from the pre and facelift transmission and then find a press release from honda or magazine review etc that highlights the fd change between model years.

If i was you I'd avoid generic mechanics and dealers and go to a honda specialist/tuner and tell them the story to date. It will be cheaper overall.

62397


62398


Countershaft is your fd, diff pn. Crown wheel should be different too.
 

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Whilst you may be right, I still don't see why a few percent difference would stop the IMA from invoking regen charging when you lift off the gas, or apply the brakes, and yet there would be no fault code anywhere. (if there isn't one logged somewhere)?
 
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