Left Turn signals blink very rapidly - Right Turn signals fine - 2003 Grand Marquis - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

rdondes · 01-30-2012, 10:01

My 2003 Mercury Grand Marquis has 132,000 miles on it. Yesterday, out of the blue, the left turn signals began blinking very rapidly. The right turn signals blinks at the normal speed. I thought either the front or rear blinker bulb would be burned out - that has been my experience over the past 30 years. However that is not the case. The left front and left rear turn signals blink fine - just very rapidly.

Can anyone offer a suggestion as to why this is happening and is there a fix for it?

Thanks,
Richard
email: rdondes@comcast.net

**Bert** · 01-30-2012, 11:13

There are more than one bulb in each rear light and if one burns out, they flash fast.

rdondes · 01-30-2012, 14:33

Quote:

Originally Posted by Bert

There are more than one bulb in each rear light and if one burns out, they flash fast.

**************************************

Thanks Bert. That is exactly what the problem was. The outside bulb on the rear, driver-side of the car was burned out. It is a Sylvania 3157K/3157LL. I replaced it and the left-side turn signals now blink at normal speed.

Thanks..!!

Richard

**Bert** · 01-30-2012, 15:46

You're welcome. Thanks for the update.

ru49manfred · 02-07-2012, 15:42

Hi Richard,
We have a C/Vic p71 2007 and it is doing exactly what yours is doing, I have been to the dealers and they said it usually means you have a bulb gone bad, I they sold me front and rear and they are now in place, but no difference. John

**Bert** · 02-07-2012, 15:48

Are the 2 bulbs on each side working? You have to look close. If one in the rear, which has 2 in each side, quit, they wil flash faster on that side.

rdondes · 02-07-2012, 15:54

Quote:

Originally Posted by Bert

Are the 2 bulbs on each side working? You have to look close. If one in the rear, which has 2 in each side, quit, they wil flash faster on that side.

*************************************************
Hi, I fixed this problem last week from the information in this thread from Bert.

Each of the rear light housing have 2 bulbs in them (3157K/3157LL). The outside bulb on the rear, driver-side of the car was burned out. It is a Sylvania 3157K/3157LL. I replaced it and the left-side turn signals now blink at normal speed.

Now that I know what to look for, it is easy to diagnose. Just look at each rear light when the turn signal is on. The side that is blinking at normal speed will have both bulbs blinking. Then, when you look at the side that is blinking rapidly, you'll clearly see that only one bulb is blinking. Unbolt the light housing from the inside of the trunk, replace the bulb, and all will be fixed.

Thanks again Bert.

Richard...

rdondes · 02-07-2012, 15:57

Quote:

Originally Posted by ru49manfred

Hi Richard,
We have a C/Vic p71 2007 and it is doing exactly what yours is doing, I have been to the dealers and they said it usually means you have a bulb gone bad, I they sold me front and rear and they are now in place, but no difference. John

*******************************************

I hope you didn't get ripped off. The front signal housings are difficult to remove due to limited space.

Each of the rear light housings have 2 bulbs in them (3157K/3157LL). If one of the bulbs on either side, the inboard or outboard bulb is burned out, that side will blink very rapidly.

Now that Bert instructed me on what to look for, it is easy to diagnose. Just look at each rear light when the turn signal is on. The side that is blinking at normal speed will have both bulbs blinking. Then, when you look at the side that is blinking rapidly, you'll clearly see that only one bulb is blinking. Unbolt the light housing from the inside of the trunk, replace the bulb, and all will be fixed. You'll have to peel back the trunk lining a bit, but it will go back into place.

Thanks again Bert.

NoLeaks2001 · 02-07-2012, 16:44

If replacing the bulbs doesn't fix the rapid flashing, there was a Technical Service Bulletin dated Apr.30, 2002 that adressed this problem. Here it is without the illistrations (which I don't know how to transfer);

Quote:

FORD:
1998-2002 CROWN VICTORIA MERCURY:
1998-2002 GRAND MARQUIS

This article is being republished in its entirety to update the Service Procedure and to update the parts required. ISSUE:

Some vehicles produced before 3/5/2002 may exhibit an intermittent rapid flashing of the turn signals. This may be caused by bulb outage, circuit ground or circuit integrity. Ensure the turn signal fast flash is not due to bulb outage, then verify good continuity at all ground screws.
ACTION:

If condition is not resolved, replace the Lighting Control Module with the latest level part. Refer to the following Service Procedure for details.
SERVICE PROCEDURE

If normal diagnostics does not correct the condition, replace the Lighting Control Module with the latest engineering level as follows:

Disconnect the battery ground cable. For additional information refer to Workshop Manual Section 14-01 for 1998 model year; 414-01 for 1999-2002 model year.
Remove the LH instrument panel lower insulator ( Figure 1 ).
1. Remove the pin-type retainers ( Figure 1 , Detail 1).
2. Disconnect the courtesy lamp ( Figure 1 , Detail 2).
If equipped with adjustable pedals (model years 2001-2002), remove the accelerator pedal and shaft. For additional information, refer to Section 310-02 of the Workshop Manual.
Position the LCM aside.
1. Remove the screws ( Figure 2 , Detail 1).
2. Release the locking tab ( Figure 2 , Detail 2).
Disconnect the electrical connectors and remove the LCM ( Figure 3 ).
To install, reverse the removal procedure. Check for correct operation.

LABOR OPERATION CLAIMING CHART Operation Labor Description Vehicle Time 020907A Replace Lighting Control Module Vehicles With Adjustable Pedals 0.6 Vehicles Without Adjustable Pedals 0.4

PART NUMBER PART NAME XW7Z-13C788-BA Lighting Control Module - 1998-1999 YW7Z-13C788-CA Lighting Control Module - 2000 1W7Z-13C788-BC Lighting Control Module - 2001-2002

OTHER APPLICABLE ARTICLES:

NONE
SUPERSEDES:

01-21-3
WARRANTY STATUS:

Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage
DEALER CODING

BASIC PART NO. CONDITION CODE 13C788 42
OASIS CODES:

201000, 201100, 201200, 206000

[IMG]file:///C:/TSO/tsocache/BRIAN_2592/T20907~us~en~file=tb6621a.gif~gen~ref.gif[/IMG]
Figure 1 - Article 02-9-7

[IMG]file:///C:/TSO/tsocache/BRIAN_2592/T20907~us~en~file=tb6622a.gif~gen~ref.gif[/IMG]
Figure 2 - Article 02-9-7

[IMG]file:///C:/TSO/tsocache/BRIAN_2592/T20907~us~en~file=tb6623a.gif~gen~ref.gif[/IMG]
Figure 3 - Article 02-9-7

Copyright © 2002 Ford Motor Company

**Bajarider** · 02-07-2012, 17:12

In my opinion, if no bulbs are burnt out, then this problem is caused by a Ford goof. The LCM on certain year Panthers is energized by the same circuit as the HVAC and is VERY sensitive to volt/power flux, by design. That's how it "knows" when a light is burnt out and the power draw is also what causes it to flash.

If your turn signals operate OK with the HVAC off, but flash erratically with the HVAC and/or blower on, then it is caused by voltage flux in the circuit mentioned.

LCM's are expensive and if this is the symptom you have, then this problem can easily be fixed by connecting the LCM to a more stable circuit. This fix will save save you $400.