Ocasional CEL, no codes, runs like a dream
Thread Starter
H-T White Ops
Joined: Feb 2004
Posts: 17,603
Likes: 22
From: USA
Ocasional CEL, no codes, runs like a dream
1988 CRX Si. Entirely stock save for deck, speakers, and an aftermarket cruise control booster that's waiting to be pulled.
CEL illuminates intermittently. No code ever flashes on ECU. Drives smooth, runs smooth, electrical components operate wonderfully (sunroof a little meh halfway through shutting), 28mpg or so (should be better but I've done zero maintenance so far).
This car had a LOT of aftermarket wiring when I purchased it (cruise control, alarm, stereo, speakers, antenna). The issue has predated removing said wiring.
Ideas for the occasional CEL? Is this a known issue?
I'm leaning towards checking wiring for the CEL indicator, since zero flashes leads me to believe it's either a bad ECU (per the FSM) or a wire grounding out. Since the CEL is only on on occasion I'm leaning towards it NOT being a bad ECU.
Gauge cluster C709 (B2). To Dash fuse box C702 (B10), Fuse number 1 (10A).
Gauge cluster C709 (B5). To ECU C452 (B13).
C452 : (20-BLK) : On PGM-FI ECU
C702 : (18-WHT) : On dash fuse box
C709 : (12-WHT) : On left rear of gauge assembly
CEL illuminates intermittently. No code ever flashes on ECU. Drives smooth, runs smooth, electrical components operate wonderfully (sunroof a little meh halfway through shutting), 28mpg or so (should be better but I've done zero maintenance so far).
This car had a LOT of aftermarket wiring when I purchased it (cruise control, alarm, stereo, speakers, antenna). The issue has predated removing said wiring.
Ideas for the occasional CEL? Is this a known issue?
I'm leaning towards checking wiring for the CEL indicator, since zero flashes leads me to believe it's either a bad ECU (per the FSM) or a wire grounding out. Since the CEL is only on on occasion I'm leaning towards it NOT being a bad ECU.
Gauge cluster C709 (B2). To Dash fuse box C702 (B10), Fuse number 1 (10A).
Gauge cluster C709 (B5). To ECU C452 (B13).
C452 : (20-BLK) : On PGM-FI ECU
C702 : (18-WHT) : On dash fuse box
C709 : (12-WHT) : On left rear of gauge assembly
DO IT ON ALL FOURS
Joined: Sep 2007
Posts: 7,632
Likes: 15
From: IN Your Mind
Re: Ocasional CEL, no codes, runs like a dream
Why bump after 7 hours? This section doesn't move like it used to.
Obviously it isn't normal. Since the car had the wiring hacked up then start there, obviously.
Obviously it isn't normal. Since the car had the wiring hacked up then start there, obviously.
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Joined: Jul 2004
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Likes: 514
Re: Ocasional CEL, no codes, runs like a dream
Try unplugging a sensor like the IAT sensor to trigger a CEL, then see if you can retrieve the trouble code to try to rule out the ECU as the source.
Check grounds G101 for the ECU and G1 for the battery.
Check the Grn/Orn wire that goes from the ECU to the gauge's Check Engine Warning Light. There may be an intermittent short being caused if that wire's insulation is chafed and rubs against body ground or another ground wire. The warning light will receive power/voltage (+) via the dash No. 1 fuse when in RUN or START, it just needs the ground (-) coming from the ECU via that Grn/Orn wire to illuminate. Also, look at Connector C405, that Grn/Orn wire runs through it.
Check grounds G101 for the ECU and G1 for the battery.
Check the Grn/Orn wire that goes from the ECU to the gauge's Check Engine Warning Light. There may be an intermittent short being caused if that wire's insulation is chafed and rubs against body ground or another ground wire. The warning light will receive power/voltage (+) via the dash No. 1 fuse when in RUN or START, it just needs the ground (-) coming from the ECU via that Grn/Orn wire to illuminate. Also, look at Connector C405, that Grn/Orn wire runs through it.
Last edited by tech8; Oct 11, 2014 at 09:35 PM. Reason: image removed
Thread Starter
H-T White Ops
Joined: Feb 2004
Posts: 17,603
Likes: 22
From: USA
Re: Ocasional CEL, no codes, runs like a dream
I never implied it was normal. Don't you think "check the wiring" is a bit vague? I didn't yank anything out. I very meticulously removed it and the issue was happening before any of that wiring was removed. None of the aftermarket wiring appeared to do with anything as far as engine sensors.
Try unplugging a sensor like the IAT sensor to trigger a CEL, then see if you can retrieve the trouble code to try to rule out the ECU as the source.
Check grounds G101 for the ECU and G1 for the battery.
Check the Grn/Orn wire that goes from the ECU to the gauge's Check Engine Warning Light. There may be an intermittent short being caused if that wire's insulation is chafed and rubs against body ground or another ground wire. The warning light will receive power/voltage (+) via the dash No. 1 fuse when in RUN or START, it just needs the ground (-) coming from the ECU via that Grn/Orn wire to illuminate. Also, look at Connector C405, that Grn/Orn wire runs through it.
Check grounds G101 for the ECU and G1 for the battery.
Check the Grn/Orn wire that goes from the ECU to the gauge's Check Engine Warning Light. There may be an intermittent short being caused if that wire's insulation is chafed and rubs against body ground or another ground wire. The warning light will receive power/voltage (+) via the dash No. 1 fuse when in RUN or START, it just needs the ground (-) coming from the ECU via that Grn/Orn wire to illuminate. Also, look at Connector C405, that Grn/Orn wire runs through it.
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