Headlight flicker?
 

I have noticed recently on several occasions the headlights on our 2007 Accord will dim ever so slightly for a split second. I thought at first it might be due to the compressor kicking on but it does it even with all aspects of the climate control system off. Short in the wiring somewhere? Any ideas?

Maybe not. For years now, Honda has had a control system for it's alternators, where the ECU can shut off the alternator completely under the following conditions...
1) engine all warmed up & happy
2) voltage at least xx volts (whatever the magic number)
3) very little load (measured by the ELD)

When this happens, the voltage drops a bit. Dimming headlights are subtle evidence that this is going on.

Thanks a lot for the explanation Jim. I've been paying more attention to it recently and it does it at any speed, in any gear (5 spd), whether there is a load on the engine or no load at all. Your explanation would make sense then. Would it be possible to feel an ever so slight miss/hesitation when this happens? I swear I can feel this in the seat of my pants when the lights dim.....my wife thinks I'm losing it!

Thanks again,

Scott

I wouldn't expect you could feel anything, unless it actually IS the AC compressor clutch engaging. But you said the climate control system was shut off. Are you sure the AC isn't on for defrost? That thing runs stealth-mode. When you select any form of windshield defrost, it runs the AC without even turning on the green AC pilot light.

If you have auto climate control, there's all kinds of computerized magic happening in there.

That is what I'm feeling then because it does have auto climate control. I'm going to pay closer attention to the headlight flicker and see if the slight hesitation actually coincides with it while the auto climate control is being utilized. Just got back from a meeting on the road and noticed the occasional hesitation but I had the auto climate control on the whole trip. thanks again for the information.

Scott

I've had an 2009 EX-L (4 cyl) for about 6 weeks and I thought I was imagining things... Seems like cycling the voltage on and off like that would be hard on delicate electronics.. Has anyone had any electrical issues caused by this?

Headlight Dim / DTC P1298
 

I found TSB 05-034, applicable to many models.

Service Bulletin
© 2005 American Honda Motor Co., Inc. – All Rights Reserved ATB 28971-31552 (0512) 1 of 4
CUSTOMER INFORMATION: The information in this bulletin is intended for use only by skilled technicians who have the proper tools, equipment,
and training to correctly and safely maintain your vehicle. These procedures should not be attempted by “do-it-yourselfers,” and you should not assume
this bulletin applies to your vehicle, or that your vehicle has the condition described. To determine whether this information applies, contact an
authorized Honda automobile dealer.
December 14, 2005
05-034
Applies To: See VEHICLES AFFECTED
Headlights Dim or DTC P1298 Is Stored in the ECM/PCM
(Supersedes 05-034, dated September 13, 2005, to update the information marked with the black bars)
SYMPTOM
The headlights dim with the engine running and the
headlights on, or DTC P1298 [electronic load detector
(ELD) circuit high voltage] is stored in the ECM/PCM
(but the headlights do not dim).
PROBABLE CAUSE
The ELD has a faulty solder joint.
VEHICLES AFFECTED
2003–04 Accord – ALL
2005 Accord (L4 2-door):
From VIN 1HGCM7...5A000001 thru
1HGCM7...5A006329
2005 Accord (L4 4-door):
From VIN 1HGCM5...5A000001 thru
1HGCM5...5A035840
From VIN 3HGCM5...5G700001 thru
3HGCM5...5G701907
All Japan-built (VIN begins with JHM)
2005 Accord (V6 2-door):
From VIN 1HGCM8...5A000001 thru
1HGCM8...5A005073
2005 Accord (V6 4-door):
From VIN 1HGCM6...5A000001 thru
1HGCM6...5A017546
2003 Element – ALL
2004 Element (2WD):
From VIN 5J6YH1...4L000001 thru
5J6YH1...4L015490
2004 Element (4WD):
From VIN 5J6YH2...4L000001 thru
5J6YH2...4L037697
2005 Odyssey:
From VIN 5FNRL38..5B000001 thru
5FNRL38..5B018359
CORRECTIVE ACTION
Accord and Odyssey: Replace the under-hood fuse/
relay box.
Element: Replace the ELD.
PARTS INFORMATION
Electronic Load Detector:
P/N 38255-S5A-003, H/C 7987571
Under-hood Fuse/Relay Box:
2003–04 Accord L4 – 2-door LX/EX, 4-door EX
P/N 38250-SDA-A21, H/C 7136617
2003–04 Accord L4 – 4-door DX
P/N 38250-SDA-A11, H/C 7136609
2003–04 Accord L4 – 4-door LX
P/N 38250-SDA-A01, H/C 7136591
2003–04 Accord V6 – All
P/N 38250-SDB-A21, H/C 7136641
2005 Accord L4 – DX
P/N 38250-SDA-A12, H/C 7773799
2005 Accord L4 – LX
P/N 38250-SDA-A02, H/C 7773781
2005 Accord L4 – EX
P/N 38250-SDA-A22, H/C 7773807
2005 Accord V6 – All
P/N 38250-SDB-A22, H/C 7773831
2005 Odyssey – LX
P/N 38250-SHJ-A01, H/C 7708191
2005 Odyssey – EX, EX-L, Touring
P/N 38250-SHJ-A21, H/C 7708209
WARRANTY CLAIM INFORMATION
In warranty: The normal warranty applies.
Failed Part: P/N 38255-S5A-003
H/C 7987571
Defect Code: 03217
Symptom Code: 07411
Skill Level: Repair Technician
Out of warranty: Any repair performed after warranty
expiration may be eligible for goodwill consideration by
the District Parts and Service Manager or your Zone
Office. You must request consideration, and get a
decision, before starting work.
OP# Description FRT
7301A1 Accord and Odyssey - replace the underhood
fuse/relay box
0.5
121195 Element - replace the ELD 0.4
2 of 4 05-034
DIAGNOSIS
If the headlights dim when the engine is running,
connect the HDS to the DLC:
1. With the HDS in the PGM-FI Data List, start the
engine, and let it idle.
2. Turn on the headlights.
3. Monitor the ELD value on the Data List.
• If the ELD value is less than 18 amps:
- For Accord, go to REPAIR PROCEDURE A –
ACCORD
- For Odyssey, go to REPAIR PROCEDURE B –
ODYSSEY
- For Element, go to REPAIR PROCEDURE C –
ELEMENT
• If the ELD value is greater than 18 amps,
disregard this bulletin, and continue with normal
troubleshooting.
NOTE: A faulty ELD may cause the charging
system to fluctuate between 12.5-volt and 14.5-volt
modes with the engine running and the headlights
on. This fluctuation causes the headlights to dim.
Under normal operating conditions, the charging
system operates in the 14.5-volt mode.
If the headlights do not dim, but DTC P1298 is stored
in the ECM/PCM:
• For Accord, go to REPAIR PROCEDURE A –
ACCORD
• For Odyssey, go to REPAIR PROCEDURE B –
ODYSSEY
• For Element, go to REPAIR PROCEDURE C –
ELEMENT
NOTE: When DTC P1298 is set, the charging system
is fixed in the 14.5-volt mode, preventing the headlights
from dimming.
REPAIR PROCEDURE A – ACCORD
1. Replace the under-hood fuse/relay box:
• Refer to page 22-71 of the 2003–05 Accord
Service Manual, or
• Online, enter keyword UNDER-HOOD REM, and
select Under-hood Fuse/Relay Box Removal
and Installation from the list.
2. If necessary, clear the DTC with the HDS.
REPAIR PROCEDURE B – ODYSSEY
1. Replace the under-hood fuse/relay box:
• Refer to page 22-85 of the 2005–06 Odyssey
Service Manual, or
• Online, enter keyword UNDER-HOOD REM, and
select Under-hood Fuse/Relay Box Removal
and Installation from the list.
2. If necessary, clear the DTC with the HDS.
REPAIR PROCEDURE C – ELEMENT
1. Make sure you have the anti-theft code for the
audio system. Write down the customer’s audio unit
presets.
2. Disconnect the negative battery cable from the
battery.
3. Remove the under-hood fuse/relay box cover.
4. Release the three clips, and remove the underhood
fuse/relay box from the holder. Release the
wire harness clip from the fuse/relay box holder.
WIRE
HARNESS
CLIP
(Disconnect.)
UNDER-HOOD
FUSE/RELAY
BOX
CLIPS
CLIP
UNDER-HOOD
FUSE/RELAY
BOX HOLDER
HOLDER
05-034 3 of 4
5. Remove the lower cover from the fuse/relay box.
6. Disconnect the 3P ELD connector.
7. Remove the four screws that hold the two fuses,
then remove the fuses.
8. Release the tab that holds the ELD, and pull up on
the ELD to remove it.
9. Remove the bus bar from the ELD, and insert the
bar into the new ELD.
10. Install the new ELD and bus bar.
11. Reinstall the two fuses.
12. Reconnect the 3P ELD connector, and reinstall the
lower cover onto the fuse/relay box.
13. Reinstall the fuse/relay box and the wire harness
clip onto the holder.
UNDERSIDE OF THE
FUSE/RELAY BOX
LOWER COVER
(Pry off.)
TABS
(Six places)
3P ELD CONNECTOR
FUSE 50A
(Retain.)
FUSE 100A
(Retain.)
ELD
(Replace.)
ELD
TAB
BUS BAR
(Retain.)
4 of 4 05-034
14. Reinstall the fuse/relay box cover.
15. Reconnect the negative battery cable.
16. Clear the DTC.
17. Reset the power window control unit:
• Turn the ignition switch to ON (II), and make sure
the driver’s window AUTO function does not
work.
• Start the engine.
• Push down the driver’s power window switch to
the second detent (AUTO down) to lower the
driver’s window all the way down. When the
window reaches the bottom, hold the switch in
the AUTO down position for 2 more seconds.
• Pull up the driver’s power window switch to raise
the driver’s window all the way up without
stopping. When the window reaches the top, hold
the switch in the up position for 2 more seconds.
• If the driver’s window AUTO function does not
work, repeat this power window control unit reset
procedure.
18. Do the idle learn procedure:
• Make sure all electrical items (A/C, audio unit,
defogger, lights, etc.) are off.
• Start the engine, and let it warm up to its normal
operating temperature (the cooling fans cycle
twice).
• Let the engine idle (throttle closed and all
electrical items off) for 10 minutes.
19. Enter the audio system anti-theft code, and set the
clock. Enter the audio unit presets.

Same here
 

Just bought an 08' Accord and this happens all the time on my car. The TSB would make sense but that was for 05's. Has anyone else been having this problem with newer models?

I have a similar issue on my 2003 V6, but I would say the headlights get brighter, not dimmer. As I gently accelerate, the heaadlights get significantly brighter at precisely 50 MPH and stay bright as long as I am bove 50. It is NOT dependant on rpm as I can be coasting down a hill in neutral or accelerating hard and the lights will get brighter when I reach 50. They also sometimes get brighter when I let off the gas at lower speeds but this is more difficult to pin point. I have had the alternator tested (Autozone...) and the battery is brand new and nothing has changed. I am not sure but I may have noticed dash lights dimming/brightening corresponding to the headlights. Is this the ELD thing or is there something else? I don't want to spring for a new fuse box ($300-$400) if I don't have to. Thanks.

isnt a problem in my books, my 98 accord has its headlights dim everytime i go to roll the windows up/down. its just the extra load which draws current for a slight second before it compensates. the dim is for a second though, so if ur rolling ur windows down completely, the lights will only dim for 1second even if u continue.