1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. Welcome To LandyZone!

    LandyZone is the biggest Land Rover forum on the net. We have plenty of very knowledgable members so if you have any questions about your Land Rover or just want to connect with other Landy owners, you're in the right place.

    Registering is free and easy just click here, we hope to see you on the forums soon!

Freelander 1 Battery light flashing, erratic idlING

Discussion in 'Land Rover Freelander' started by Dreamed, Jun 28, 2019.

< Previous Thread | Next Thread >
  1. Dreamed

    Dreamed Member

    Joined:
    May 23, 2017
    Posts:
    69
    Likes Received:
    0
    Location:
    Edinburgh
    Hi guys!

    Driving home from MOT , battery light started flashing. At first from time to time, but 3-4 days along the line it always shows up a few miles after startup. Maybe it has to do with heat because light never flushes immediately after start (cool engine). The usual trigger is when I get on bumpy roads. If light doesn't flash while driving, it almost always flashes when I come to a stop in the parking lot. I normally let the car idle for 30 seconds or so before I shut down the engine and this is when it happens. Lately, idle is also erratic when this happens.

    What I checked:

    Battery voltage: 14.18 - 14.4V at idle and under load (lights) about the same. So the alternator charges!!
    Voltage between starter and battery earth = Voltage between alternator and battery earth = battery voltage.

    Blue and Green Cable going from the alternator to ECU pins show less than 1.2 ohm resistance (between ECU and harness connecting to the alternator). I checked what was visible and they don't seem broken.

    If I unplug the blue/green cable harness, idle goes back to normal, no more ups and downs.

    I'm not exactly sure how or what to measure in regards to green/blue cable but:

    Voltage coming from green cable at the harness is always fluctuating at idle. Sometimes 11.2 Volts, sometimes 10V, sometimes 13V, but never over 13.8V. So this is a clue.

    Blue cable has a low voltage. 0.2V or so. Manual says blue cable is responsible for transmitting a PMW signal to ECU to calculate electrical load on the alternator. So no idea how to test that.

    If green cable is responsible for telling the alternator the voltage of the battery, then possibly this indicates the issue, since the voltage is always much lower than 14.2V and fluctuating.

    So how do I know if the ECU sends the correct battery voltage to the alternator? And how do I know the ECU receives the correct battery voltage info.

    I don't have extended knowledge about diodes and power distribution, but I traced the smallest cable on top of the positive terminal (most likely the one responsible for informing ECU about battery voltage). This cable goes into a diode+3 fuses attached to the outside ECU box. It's easy to spot as it's the only blob hanging around from the box. There are 4 terminals going into the diode. 2 of them show exactly the same voltage as the battery (12.6V engine off). the other 2 show 1-2 voltage less, but are not identical (one is less than the other). Also the red/white cable that apparently is supposed to tell the ECU the battery voltage shows less than the actual battery voltage (something similar to those 2 above).

    If this means anything to anybody, or need more info, please let me know.

    Thank you so much!
     
  2. GrumpyGel

    GrumpyGel Well-Known Member Full Member

    Joined:
    Oct 31, 2013
    Posts:
    19,062
    Likes Received:
    13,662
    Location:
    Christchurch, New Zealand
    Have you checked the fan (drive/aux) belt ?
     
  3. Dreamed

    Dreamed Member

    Joined:
    May 23, 2017
    Posts:
    69
    Likes Received:
    0
    Location:
    Edinburgh

    I recently changed those. They spin. Not sure what else to check. As far I can see they don't slip, especially when idling.
     
  4. andyfreelandy

    andyfreelandy Well-Known Member

    Joined:
    Jul 29, 2010
    Posts:
    3,126
    Likes Received:
    1,138
    Location:
    Devon
    What year and engine is it please? My circuits vary between models.
     
  5. Dreamed

    Dreamed Member

    Joined:
    May 23, 2017
    Posts:
    69
    Likes Received:
    0
    Location:
    Edinburgh
    In my description: TD4 2004 manual.
     
  6. andyfreelandy

    andyfreelandy Well-Known Member

    Joined:
    Jul 29, 2010
    Posts:
    3,126
    Likes Received:
    1,138
    Location:
    Devon
    Looks like the green wire activates the field windings and this is fwd from fuse 19 in the 'inside of car' fusebox. This should be steady battery voltage otherwise the alternator will wobble! Check supply at this fuse and also if fuse contacts are tight. Not sure if this what is happening here but the field windings need higher levels of excitation at slower revs so that looks possible as a problem in your case.
     
  7. Dreamed

    Dreamed Member

    Joined:
    May 23, 2017
    Posts:
    69
    Likes Received:
    0
    Location:
    Edinburgh
    Ok so, after investigating everything I could, I realised the problem was in my face. Some weeks ago I dismantled the front bumper. I remember meddling with the wires that go under the intercooler and connect to horn and lights (not sure where they go from there underneath; maybe bumper impact sensor)

    As I checked the drive belt I saw these wires rubbing against the belt pulley and therefore creating a short or circuit break. I still don't understand how these would make battery light blink, but hey, problem solved as soon as I isolated the wires and re-connected broken coppers.

    Happy!
     
  8. andyfreelandy

    andyfreelandy Well-Known Member

    Joined:
    Jul 29, 2010
    Posts:
    3,126
    Likes Received:
    1,138
    Location:
    Devon
    Probs damaged the alternator sense / field wire in same loom.
     
< Previous Thread | Next Thread >