Pontiac Turn Signal Diagnose




Introduction: Pontiac Turn Signal Diagnose

The left turn signal in my 2000 Pontiac was acting up.  The mechanic told me it was a common failure and would cost around $200 to replace.  Even the electronic flasher would be $40-50 to replace.  So, I couldn't afford to just start replacing things.

I decided to tear down this device, determine the pin out, and make sure what exact component needed replacing.  I figured someone else might benefit from my experience.

Disclaimer:  Air Bags.  You should know what that means.  If you don't, stay away from this. 

I did not disconnect anything.  But, I kept all arms and other body parts away.  I have seen these things blow people out of a car!.  http://www.youtube.com/watch?v=b1Qj75pbl8o

Step 1: Remove Cover and Signal Module

My steering wheel has a two piece plastic cover with three screws.  The screws are in the bottom.  Somebody had been working with mine because one of the screws was missing.

After removing the cover,  there are only two phillips head screws holding the module in place.  As you remove the module, carefully release the cable connector from the rear.

Step 2: Cover Removal Step 1

The cover of the module is secured by three tabs and three screws. The screws are "star" type heads.  However, I was able to use a normal allen wrench.

Step 3: Cover Removal Step 2

Use a small slotted screwdriver to release the tabs in the order indicated.  I released Tab #1, then used my thumb to keep the cover up while I released Tab #2.  At this point, you can raise the cover about 3/16".  Then, use the small screw driver to release Tab #3.

Step 4: Circuit Board Map

The circuit board is held in place on the cover with two small plastic clips.  There is no need to remove this, but you should know it will come off.

I have mapped out the circuit board.  At least, the items I could determine.  The mechanical operation is quite simple.  The connectors (more in these later)  Slide over the copper traces to complete circuits.   There are a couple of special notes.

The first is that there is a black tape covering the copper to create an open circuit.

Also, the speed control is a set of broken copper traces. Each little segment feeds in to a ceramic type item that appears to be resistors in a series or maybe just a solid ceramic device.  So, each subsequent selection decreases the resistance.  (To control some sort of flip-flop ciruit or just input to a microntroller.)

Step 5: Connectors

The handle is a complex little mechanism that turns, moves, and pushes buttons based on how you move it.  It is common to all turn signals, but broken out like this it is fascinating to see the complexity.

I have a little video of the mechanism in operation.

Step 6: Video of Mechanism Internals

Step 7: Connector Pinout

Here is the connector pin out the best I could determine.

1. Flasher (N/C)
2. Flasher
3. Right Blinker
4. Right Blinker
5. Momentary Wiper
6. Wiper Speed Control In
7. Wiper Speed Control Out
8. Battery Ground ( - )
9. Headlight Common
A. Dim
B. Washer Fluid
C. Bright

On the wiper controller - it appears to be just a sensor loop to measure the resistors.

The turn indicators are just on/off.  When the mechanism slides one way, it completes the circuit for that signal. The flashing is performed by an electronic flash module. ( I think I saw this referred to as a DLR - but I don't know that that stands for.)

Step 8: Wrap-Up

When I finally got everything mapped out, I was able to determine this mechanism was operating normally.  However, I was about to use jumpers now and test the left and right turn indicator circuit. I took out the electronic flasher module and found out the map of that as well.  (I will do another instructable on that.)

Some points/issues:

1. Again - Air Bags!   Nuff Said?

2. Make sure you don't wipe the "grease" off the circuit board.  That is actually conducting grease.  I used a small bladed screwdriver to redistribute the grease on the copper traces that looked brighter than the others.

3. There is a small clip that creates an on/off action for the flasher button.  If it falls out, your button won't stay down.  Test that after you replace the cover.  (Don't wait until you completely replace all the covers !! )

4. Air Bags.

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    Phil B
    Phil B

    11 years ago on Introduction

    I am wondering if your car is a Pontiac Grand Am. I just did an Instructable on the Cruise Control On/Off switch used on the Grand Am and also on the Olds Alero. I am also wondering if you solved your turn signal problem.


    Reply 11 years ago on Introduction

    No, this is a van. Yes I solved my problem - but it included an order for around $40. I was not able to diagnose the failing component of the flasher - so I just bought a new one. My wife was not going to put up with my rig job for more than a few days!

    Phil B
    Phil B

    Reply 11 years ago on Introduction

    Thank you for the response. I understand about wives and their lack of willingness to endure clever non-factory fixes. A couple of years before Instructables our oven timer quit and a new timer was no longer available for that oven. Here is the Instructable I did on my fix. I liked it very much. It timed the oven down to the minute. But, my wife found setting the digital timer confusing. She then found a reason to buy a new oven, cooking countertop, and exhaust fan for a couple thousand dollars.