Tachometer and Speedometer aren't working .

[eK_Sedan]

Car is running as we speak . No CEL has been thrown . I let it warm up to normal operating temp, I'm about to turn the car off and check the fuse .

 

[RonJ]

Car is running as we speak . No CEL has been thrown . I let it warm up to normal operating temp, I'm about to turn the car off and check the fuse .

If the fuse is fine and no code is thrown, then do nothing with respect to code 8, unless code 8 is thrown again.

Refocus on the tachometer problem and the blue wire.

 

[eK_Sedan]

Just checked fuse .. still good .

First and foremost thank you, you really have been a lot of help throughout this whole process . I really appreciate !

Secondly, I read that the blue tach wire runs from the distributor to the driver side firewall/strut tower . In the pictures I sent there was an open on one of the blue wires in that region, could that be my problem ?

 

[RonJ]

The tach signal for your car comes from ECU pin A19 not the distributor.

Test whether the blue wire has continuity between A19 and the cluster connector pin C8.

The blue wire runs as follows:

ECU ---> connector C442 ---> connector C411 ---> cluster

The two connectors are described here:

 

[eK_Sedan]

No readings at A19 and I haven't had a reading at C8 since I started the test .

 

[RonJ]

No readings at A19 and I haven't had a reading at C8 since I started the test .

Ground the C8 cluster connector terminal to the metal frame under the dash and then test for continuity to body ground (metal frame under dash) at ECU connector terminal A19.

 

[eK_Sedan]

Okay . Will do the test in the morning . I went out driving for a bit and my check engine light came back on. When I went to give it gas my car would buck like crazy so I had to feather the gas til I got home .. once I got home I pulled the code and instead of one i had three (8-14-17) . I have a video of it as well. Even tho I had code 17 again my speedo still worked . I'm thinking because there's no Dielectric Grease ..

8 : Top Dead Center Sensor
14 : Idle Air Control Valve
17 : VSS Speed Sensor

 

[RonJ]

8 : Top Dead Center Sensor

Redo the C20-C21 resistance and short tests. If no problems are found, then the ECU is likely bad.

14 : Idle Air Control Valve

Check whether the connector is plugged into the IACV. If so, clean the IACV.

17 : VSS Speed Sensor

Test the Blu/Wht VSS wire for continuity between the VSS and ECU connectors.

 

[eK_Sedan]

Redo the C20-C21 resistance and short tests. If no problems are found, then the ECU is likely bad.



Check whether the connector is plugged into the IACV. If so, clean the IACV.



Test the Blu/Wht VSS wire for continuity between the VSS and ECU connectors.

When I checked resistance between the RED and GRN wires at the ECU I was getting the same readings as yesterday (364) .. then I tried the short test, body to ground I got nothing.

The plug was fine on the IACV. It didnt have the rubber gasket thats supposed to be on it but I took it off and I'm now about to clean it .

Checked to see if VSS plug was still getting power, BLU/WHT wire went up a bit from yesterday (4.64) BLK/WHT (11.62). Checked the VSS Wire connected to the ECU on plug C. I got (2.0)

Got my hands on and obd2 scanner .
P1359 CKP/TDC CONNECTOR DISCONNECTED
That's the only code I'm getting no 17 or 14

 

[RonJ]

When I checked resistance between the RED and GRN wires at the ECU I was getting the same readings as yesterday (364) .. then I tried the short test, body to ground I got nothing.

Got my hands on and obd2 scanner .
P1359 CKP/TDC CONNECTOR DISCONNECTED
That's the only code I'm getting no 17 or 14

Borrow an ECU for testing or source a replacement.

Checked to see if VSS plug was still getting power, BLU/WHT wire went up a bit from yesterday (4.64) BLK/WHT (11.62). Checked the VSS Wire connected to the ECU on plug C. I got (2.0)

For some reason, you won't do the VSS circuit test I suggested. If code 17 returns, you need to do the test.

You also need to do the blue tach wire test. Not much to discuss until you provide results.

 

[eK_Sedan]

When I do the short test do I have to ground the opposite end of wire that I'm testing ?

I thought I did the VSS test to the ECU correctly . I tested the BLU/WHT wire on the C connector at the ECU 200 ohm, grounded black probe to body and got 2.0 ohms. That's with the gauge cluster & VSS plugged in , should I unplug the cluster and re-test ?

And the blue tach wire diagram looks scary . Lol . But I will tackle it in the morning ..

 

[RonJ]

When I do the short test do I have to ground the opposite end of wire that I'm testing ?

No. One meter probe touches the wire terminal to be tested and one meter probe touches body ground.

I thought I did the VSS test to the ECU correctly . I tested the BLU/WHT wire on the C connector at the ECU 200 ohm, grounded black probe to body and got 2.0 ohms. That's with the gauge cluster & VSS plugged in , should I unplug the cluster and re-test ?

Where did I recommend this^ test? Please read my posts carefully.

However, there's no point in testing the VSS circuit unless code 17 is thrown or the speedometer stops working.

And the blue tach wire diagram looks scary . Lol . But I will tackle it in the morning ..

Do you have any specific questions? I mentioned the specific test that should be done.

 

[eK_Sedan]

When I did the resistance test at C20-C21 I got a reading. But when I did the short test I didn't get a reading.. I went back a few post and read your post (#29) and you said It could possible be short to ground, could that be it instead of the ECU ? Because my car starts up and idles fine . Check engine light still on . Same code

Also .. I skipped a test . I never grounded the C8 wire while I tested the A19 pin, well I did today . I didn't get a reading.. possible short ?

 

[RonJ]

When I did the resistance test at C20-C21 I got a reading.

Good. No broken wire and proper resistance.

But when I did the short test I didn't get a reading

Good. Also no short.

.. I went back a few post and read your post (#29) and you said It could possible be short to ground

...but your test above failed to reveal a short.

, could that be it instead of the ECU ? Because my car starts up and idles fine . Check engine light still on . Same code

You seem to want to avoid the conclusion drawn from your own test results. Source a replacement ECU and go from there. You may find that the intermittent code 17 and the tach issue are also caused by a bad ECU.

Also .. I skipped a test . I never grounded the C8 wire while I tested the A19 pin, well I did today . I didn't get a reading.. possible short ?

No reading indicates an open not a short. Redo the test to verify and also do the same test for ECU A19 and the Blu/Wht wire in the VSS connector, the latter of which you would ground.

 

[eK_Sedan]

I just wanted to make sure I needed and ecu before I went out and bought one . I'm on my way to pick up one now, I will let you how it turns out.

I redid the tests same results . No readings. I grounded the BLU/WHT wire like you said .

 

[RonJ]

I redid the tests same results . No readings. I grounded the BLU/WHT wire like you said .

Why are you still testing this^ wire?

Is code 17 thrown? Is the speedometer not working? If not, there's a problem with how you are doing the test.

 

[eK_Sedan]

Redo the test to verify and also do the same test for ECU A19 and the Blu/Wht wire in the VSS connector, the latter of which you would ground.

^



Swapped ECU . Check engine flashes as normal, I let the car warm up to normal operating temp. Went for a drive car drove better than it did before, more responsive.. No check engine lights the Tach still doesn't work though. Everything else is good .

When I turn my lights on the alarm goes go off . Very faint but I can still hear it . I'm going to have a Radio shop look at it . For now I unplugged it.

 

[RonJ]

^

the Tach still doesn't work though.

Haha...at some point, VSS and tach tests started to get mixed up.

The ECU A19 and cluster C8 tests on the blue wire are for the tachometer problem. So, what test did you do on this circuit?

Swapped ECU . Check engine flashes as normal, I let the car warm up to normal operating temp. Went for a drive car drove better than it did before, more responsive.. No check engine lights

Great. Good progress.

When I turn my lights on the alarm goes go off . Very faint but I can still hear it . I'm going to have a Radio shop look at it . For now I unplugged it.

I can only help with alarm issues if you know how it's wired. Or is it a stock alarm system?

 

[eK_Sedan]

Haha.. I grounded the C8 wire while I tested A19 .. no readings.

The alarm is Viper . It was working fine just the other day . I don't think they did it right because the power door locks don't work at all .
All the wiring is right behind the the cruise control and sunroof button..

And AGAIN thank you ! Patience is definitely one of your virtues. Haha

Code 14 and 17 came back again. Lol . I'm buying a new VSS and a IACV .

Weird thing is, my speedo/odometer still works. So I'm thinking the sensor is bad, lord knows how long they been riding around like that and I was commuting to Los Angeles a lot while the speedometer wasn't reading ..

As for the IACV .. the car has been having high idle issues since I bought it. If I tapped the gas the idle would drop real low then go back up or somettimesit would do it by its self .. would a bad one cause the car to buck while pressing the gas ? I have to feather it like crazy just to get it to move.

 

[RonJ]

When your strategy becomes replacing parts at random, then you don't need me or a thread. For example, if the VSS were bad, the speedometer wouldn't work. Good luck.