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1999 Mercury Cougar Speedometer not working? Tested harness

Tiny
SIN360
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  • 1999 MERCURY COUGAR
Electrical problem
1999 Mercury Cougar 6 cyl Front Wheel Drive Manual 122k miles

I bought a 99 Mercury Cougar 2.5 MTX. The speedometer didn't work when I bought it. I changed out the vss tried two new ones and it still doesn't work. I have a different cluster same thing and I have also tested out the the harness with the test points the the ford shop manual for the 99 cougar says to test. I'm not sure what else to check for. I verified that the vss plug was getting power and ground; the shop manual also had another test for resistance. Here are the test the I ran. Test 1: I had to measure the resistance between HEC C808b pin 9, harness side and VSS pin 2. It states that if the resistance is less then 5 ohms to go to the next test. My resistance was less than 5 Test 2: VSS ground, test vss pin 3 and ground. If the resistance is less than 5 ohms to continue to the next test. My resistance was less than 5 Test 3: Voltage, test vss pin 1 and ground if voltage is greater than 10 volts replace the vss. My voltage was at 12. How do I check the signal when I have the car running in the air?
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Sunday, August 15th, 2010 AT 9:05 AM

13 Replies

Tiny
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Hi sin360,

Thank you for the donation.

Did you try to retrieve for trouble codes and was any found?

Do you have the complete test procedures?

I have sent you the complete test procedures, go through them and let me know what you find.
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Sunday, August 15th, 2010 AT 11:23 AM
Tiny
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I had a trouble code of p0500 before I removed my battery to do some work. It's not there now, but I'm sure it's going to come back on once I start driving it around until I get this sorted out. I'll post up my results once I get the all the test completed.
Thanks
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Sunday, August 15th, 2010 AT 11:39 AM
Tiny
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You're welcome. There are various systems used so you need to get the appropriate test done.

Keep posted.
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Sunday, August 15th, 2010 AT 12:55 PM
Tiny
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I have short somewhere here are my results.

Step 1: 58 and VSS + = less than 5
51,103 and VSS - = less than 5
I have a Cougar with the 3 pin connector those are the pins according to the diagram.

Step 2: Check Resistance between PCM connector pin
58 and 33: I don't have a wire going to 33. I guess because I have the 3 wire VSS.

58 and 103: no resistance at all
58 and 71: no resistance at all

There was no connection between the points. It tells me to go to step 12 which refers me to a wiring diagram to check the modules connected to the VSS circuit. I don't have wiring diagrams in my ford books. Do you have it by any chance? I tested it with the vss connected and disconnected and I also check every pin with pin 58 to see if had anything. So this means I have a short some where correct?
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Sunday, August 15th, 2010 AT 5:51 PM
Tiny
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I have sent you the engine wiring schematics so you can reconfirm if that is the problem.

When you mentioned no resistance, if it is 0 ohms, than is it a short. If the ohmmeter is not reading, it is an open in the circuit.
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Sunday, August 15th, 2010 AT 9:10 PM
Tiny
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Its an open circuit. The ohmmeter is not reading anything. Ok I've been looking over the diagrams and the vss testing procedures pdf that you sent me. I'm gonna have to check the different steps tomorrow because I believe that step 2 does not apply to me. Pin 33 does not apply to me because that is for a system with a 2 pin vss. Looking over the test procedures I'm positive I need to start at step 5 for my type of sensor which is a 3 pin sensor. Thank You for the help and the material. I'll keep you posted on my findings tomorrow.
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Sunday, August 15th, 2010 AT 9:26 PM
Tiny
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Happy hunting and have a nice day. :)
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Monday, August 16th, 2010 AT 8:24 AM
Tiny
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Ok I did the tests today and I got to step 9 which I'm supposed to check the VSS resistance. It was less then 5 omhs and tells me to replace the VSS. I already have replaced the VSS with two new ones. So I'm assuming is not the VSS. The last test is to check the VSS ground circuit resistance it says if the resistance is less than 5 oms which mines was; to repair open in VPWR circuit to VSS. Since I have tried two new VSS should I start checking for an open circuit in VPWR to VSS? It looks like thats were the problem is pointing after the tests I performed. I was just looking at diagram 3 that you sent me. Pin 71 (Ignition Power) goes down into a dot that connect with other wires including the VPWR pin on the VSS harness. I'm a little confused looking at the diagram where all the wires come together on that dot. What is that point supposed to be? Looking at the 3 point VSS on the pdf it shows a power relay in between the vss pin and PCM pin 71. Would the car start if that relay is bad? I don't see the relay on the wiring diagram.
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Monday, August 16th, 2010 AT 1:55 PM
Tiny
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There is a possibility the new VSS were faulty or of a different specs. Did you confirm if they were for your model?

When there is a problem with the testings, we should try to understand what has gone wrong. New components do fail and if it is from the same batch, there is a possibility more than 1 is faulty.
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Monday, August 16th, 2010 AT 3:21 PM
Tiny
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I returned the VSS and got one from a different location. Same results is it safe to assume that I might have an open in VPWR circuit to VSS according to test number 10?
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Monday, August 16th, 2010 AT 7:18 PM
Tiny
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Step 6 is for checking the power from VPWR. At VSS, was there battery voltage as per test done?

If battery voltage is available, there is nothing wrong with the circuit, except you need to check if the same voltage is available at the PCM terminal 71.

Sorry I missed out the part about the wires joining at a dot. That is the connecting point for the various sensors of the engine harness and if you have voltage at HO2S sensors, but no voltage at the VSS, then there is an open between the dot to the VSS.
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Tuesday, August 17th, 2010 AT 7:01 AM
Tiny
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Ok I'm sure all the wiring is good. I talked to my wife's uncle he has his own shop. He told me that the speedo gear needs to bee replaced or it moved out of place. He said it happens to these transmissions because the gear is plastic. Thanks for the help. I'll let you know if that solved the problem.
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Friday, August 20th, 2010 AT 12:12 PM
Tiny
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Sorry that we seem to have missed that part. Yes, it is possible and you can take the gear out to inspect for wear or damage.
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Saturday, August 21st, 2010 AT 8:05 AM

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