Voltage Issues Civic 2001

afnan.bashir (afnan.bashir) 2022-09-23 23:43:53 +0500 #1

Hi,
Been trying to resolve intermittent fluctuations in voltage in this car. The car has JDM Engine along with JDM ECU. Everything is well connected i.e., o2 is connected etc and no bypasses. No codes etc etc.

At idle the voltage at battery is around 13.9 V but at ECU its 11.8-12V. This is a significant voltage drop. I have tested grounds at ecu and it checks out. This means voltage after the fuse box is dropping. The under hood fusebox itself shows battery voltage (no drops).

To my surprise ELD is not connected. There is no connector there and ECU constantly reports 1,04A ELD PID. Strange it does not throw a code.

I am seeking hints to diagnose it and question. Did we have ELD connected in PKDM civics and can it be the reason for fluctuations?

Hassan1991 (Electrical Engineer ) 2022-09-24 03:12:21 +0500 #2

No eld in pkdm civics.
Have you check the voltages drop at ignition switch and after efi main relay?

afnan.bashir (afnan.bashir) 2022-09-24 05:41:55 +0500 #3

No, thats a fair point though. Ill do that.

afnan.bashir (afnan.bashir) 2022-09-24 08:50:50 +0500 #4

Checked the voltage on PGM FI relay 1 and 2 it is battery voltage. However, I also found that someone jumped the source to PGM FI Main relay with to another wire through the Body wiring to Engine wiring harness connector right next to the relays.

afnan.bashir (afnan.bashir) 2022-09-24 13:29:52 +0500 #5

Update: The power wire for PGM FI relay was burnt. Still showed battery voltage but under load went to zero. Provided extra source and now it does show battery voltage in battery PID through scanner.

Is this Normal that battery wires connected to the fuse box get too hot to touch? car only had AC and headlights on and at idle the alternator was 70% + but the battery voltage was 12.5V. Appears that the alternator is not couping but the battery wires getting hot means that too much amp usage. Any pointers?

Hassan1991 (Electrical Engineer ) 2022-09-24 14:31:08 +0500 #6

If you have dc clamp amp meter you can check how much amps alternator is providing and how much being draw by the car.
No wire shouldn't get hot at all. Which gauge wire it is and what is the condition of wire?

Ijaz_Ahmed (Ijaz_Ahmed) 2022-09-24 18:47:15 +0500 #7

A hot wire is a recipe for disaster, God Forbid.
Check if battery wire to the fuse box is original and has clean contacts on both sides. If it is original, Something after the fuse box is drawing too heavy current.

If not original, maybe some installed a local wire (possibly under Guage and not pure copper), then you need to change it.

Always the best to actually measure the current.