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Thread: Dash Light Flicker

  1. #1

    Default Dash Light Flicker

    As research on the forum has indicated, dash light flicker seems to be accepted as "normal" in the M400. This issue has been and irritant to me since I aquired my car a year ago. As the dash lights would dim at idle, so would the exterior lights, the fuel pump would change pitch, etc. Just not acceptable for these beautiful cars. Even though the HID's helped a bit as they dropped the voltage requirement on the system, the problem was clearly still there. But.... I think I've got an answer.

    Selling car parts every day has some advantages, namely you hear a wide variety of issues on a wide variety of cars. Dash light flicker is a common complaint on the 99 Mercury Cougar V6. So common that Mercury issued a TSB (Tech Service Bulletin) to advise their dealers on how to fix this issue. Guess what chassis our cars "borrowed" their alternator from ??? You got it, the 99 Cougar with a V6.

    Over the long weekend I did the Mercury TSB on my car. Two nights of test drives (oh, the labors I endure ) and the problem seems to be gone. Headlights, A/C, fuel pump, dash lights, blower motor, etc. all seem to recieve consistent voltage at idle, even when all are running on max.

    The TSB is simple to perform. There are three small wires in the connector that plugs into the voltage regulator on the back of the alternator, plus a main red charge wire running from the stud on the body of the alternator, through a fuse, and back to the battery. The three small wires are as follows... Blue leads back to the dash warning light, black is the "ignition wire" that excites the alternator, and the manual says the "looped wire" is white (mine was red on NUS101). See page 12 in the electrical section of the assembly manual.

    The issue lies with the black wire that "ignites" the alternator and gives it the "charge now" signal. Like Mercury, Noble plumbed this black wire in line with a couple of other items, (reverse lights, vehicle speed sensor, fuse #9, etc) which doesn't provide a clear signal on the status of the battery (whether it's in need of a charge from the alternator or not). The TSB states to cut the black wire, terminate the "car end" in the harness (or heat sheathing in our case) and attach the harness end of the black wire, along with the large red wire, to the B+ terminal (the stud where the large battery charge wire hooks up). Now the alternator has a clear picture of the status of the battery, and knows whether to charge or not. Problem solved on a 99 Cougar, and the Noble too.

    A couple of things to remember. The wires down there take a beating from heat and should be inspected. (I replaced all of mine while I had it in the air). Disconnect the negative battery cable before doing any work, the red "charge wire" to the battery is hot at all times. Lastly, I accessed the TSB via NAPA's system, but I'm sure that some "much more web savvy than I" forum member can find it and post a link, as it should be public knowledge. If not I can copy and paste.

    Mike P.

  2. #2
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    Thanks for the pointer! It is TSB 00-25-6. I found a PDF of it with step-by-step instructions and drawings here:http://www.teamwetworks.com/claymore...sb00-25-06.pdf

    Enjoy,

    a.

  3. #3
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    Thanks Mike for the tip and Tills for the TSB. I need to give this a try.

    Last year I removed the voltage regulator/brush assy from the alternator. Thought the brushes might be the source of flashing lights. Took the assy apart as much as I could. Brushes were fine. Snugly tightened the assy connections back toghether again and reinstalled it into the alternator. That procedure solved the flickering lights and occasional alternator light flicker until this spring. Flickering and an occasional alternator warning light blip at moderate rpm is back again, but I hadn't gotten around to checking it out util I read your thread today. Have been chasing another gremlin (very rough idle during first 10-20 seconds of a cold start) that might be related. Will post to another thread after I study that gremlin further.

    Bill
    2007 M400, NUS 206

  4. #4

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    If I understand this correctly, I cut the black wire in half, leave one end in the heat shielding where this wire came through and the other end I put a spade connector on it and somehow put it on the battery "+" terminal.


    My battery warning light has been flickering on/off for weeks now and this is driving me up a wall. The fuel pump doesn't hummm constantly like it use to. When the light flickers, the fuel pump humm's on/off with exact timing of the warning light. Will this fix the problem. The battery warning light never flickers at idle and sometimes won't flicker for 5-10 mutes then will barely flicker and sometimes the light flickers brightly and as said earlier, in perfect unisone with the fuel pump. Thank you.

    Ken

  5. #5
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    Ken,

    It's hard to say whether the procedure in Tills' post will solve your flicker problem, but it's worth giving doing. While you're doing that procedure, try pulling the gray plastic box out of the alternator (two screws, I think). It houses the brushes and the rectifier/voltage regulator, which can also be separate by undoing another set of screws. Check the brushes to make sure they're long enough and have good spring tension to connect to the armature slip ring. Also have a look at the slip ring to see if it's wearing smoothly. While the gray box is out check the screws that connect its two parts and make sure they're tight. If the brushes/springs don't seem right, you should be able to purchase a replacement brush set from your local Ford parts counter. The part number is on the gray box.

    If none of this works, and if all of your electrical connections, fuses and grounds are well connected, then you may need to pull your alternator and have it checked.

    Good luck Ken.
    2007 M400, NUS 206

  6. #6

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    where is the alternator and what does it look like?

  7. #7
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    Ken,

    The alternator is mounted to the lower right front of the engine. This picture is from Chapter 1, page 36 of the Noble Installation Manual. If you haven't already, I highly recommend that you get well aquainted with the manual. It's available for download in the Owners Private Forum.

    The gray box that I mentioned is on the back end of the alternator where all the wire connections are. You'll need to raise the car on stands or lift and remove the engine compartment belly pan to get to it. I hope this helps you solve your flickering light issue.


    Attachment 9060
    2007 M400, NUS 206

  8. #8

    Default

    wow, thanks for showing me where it's at. I wonder if the black wire and set of three from the alternator is heat wrapped up by the battery. I'll take a picture tomorrow. I'm going to print the manual now, thank you

  9. #9
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    Quote Originally Posted by ken7258 View Post
    wow, thanks for showing me where it's at. I wonder if the black wire and set of three from the alternator is heat wrapped up by the battery. I'll take a picture tomorrow. I'm going to print the manual now, thank you
    Ken, yes, the wire loom to the alternator is heat shrink wrapped. To make the modification recommended by the Ford tech memo, you'll need to cut it but only a short way up from the alternator. While making the mod, you should be able to fit some new heat shrink on. You won't need to add a new wire all the way back to the battery; just make take the wire over to the large battery cable terminal at the alternator and use a large enough connector to fit on the post.
    2007 M400, NUS 206

  10. #10

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    I'm confused. So I cut the black wire in half that is in the heat wrap from the 3 wire connector that is plugged into the back of the alternator. The short black piece that is left from the 3 wire connector that came from the alternator just gets terminated and stays in the heat wrap. The other end of the wire, lets call it the long piece of black wire, doesn't go to the "+" on the battery but goes to where the "+" cable from the battery is bolted into on the alternator. I guess what has changed is the black cable is now going directly to the "+" on the battery by way of the "+" cable from the battery that is bolted into the alternator. Just for my knowledge, where does the other end of the black wire end up?

    Originally the black cable from the alternator went somewhere but not directly to the battery. Since it seems this heat wrapped set of three wires runs right by the battery, couldn't I just slice open the heat wrap cut the black wire in half, terminate the end going to the alternator push it back into the heat wrap. I think there is quite a bit of extra black wire by the battery and I could see if there is way to re-route the black wire to the "+" on the battery. I think this would be exactly the same except I wouldn't have to jack up the car and remove the pan. If there isn't enough black wire up to by the battery to get it to the "+" on the battery, I wonder if it would be alright to use a female/female connect and just add some extra wire to the cut black wire and connect it to the "+" on the battery.

    Thanks for your help
    Last edited by ken7258; 09-09-2012 at 09:00 PM.

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