classic instruments - calibrating speedometer??
08-15-2010, 10:05 AM
#1
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classic instruments - calibrating speedometer?? Ok, I have all my gauges working except for my speedometer gauge. The car is a 93 Camaro with an LS1/TH400 swap. My gauges are Classic Instruments gauges.
I have the TH400 reluctor wheel/pigtail conversion; here are the part numbers I'm using:
12085498 - pigtail connector
8655315 - reluctor
24232618 - sensor
I'm having a very difficult time calibrating the speedo.
The instructions say to first identify the type of gauge I'm using by looking at the back of the gauge. Apparently, I'm using a 4 5/8" 16-PULSE speedometer. Here's what the back of it looks like:
Classic Instruments told me I needed to use an SN74 box, and wire it like this:
And that is EXACTLY how I have it wired up. On my LS1 engine harness, I have the green/white wire labeled VSS OUTPUT as my ECM Computer Speed Signal wire in the diagram. So that goes to the INPUT spot on the SN74 box. My grounds are good, the SN74 and the speedo are both getting power. So then after it's all wired up, here is the calibration process (short read): http://www.classicinstruments.com/Us...alibration.pdf
Unfortunately, when I get to 60mph using a speedometer app on my phone, hold the SN74 pushbutton down to get into Real Time calibration mode, and then click the pushbutton again, THE NEEDLE DOESN'T MOVE. I mean it doesn't move AT ALL.
Has anyone ever had experience with a Classic Instruments speedometer and an SN74 box??
I know this post is a little long but I'm not sure where to go from here. I'd call Classic's tech line, but that's the same line that told me to get the SN74 and it's not working. They're also closed on weekend which is when I have time to work on my car.
I'm so close!! One last gauge to go; thanks to anyone willing to help me out at all!
I have the TH400 reluctor wheel/pigtail conversion; here are the part numbers I'm using:
12085498 - pigtail connector
8655315 - reluctor
24232618 - sensor
I'm having a very difficult time calibrating the speedo.
The instructions say to first identify the type of gauge I'm using by looking at the back of the gauge. Apparently, I'm using a 4 5/8" 16-PULSE speedometer. Here's what the back of it looks like:
Classic Instruments told me I needed to use an SN74 box, and wire it like this:
And that is EXACTLY how I have it wired up. On my LS1 engine harness, I have the green/white wire labeled VSS OUTPUT as my ECM Computer Speed Signal wire in the diagram. So that goes to the INPUT spot on the SN74 box. My grounds are good, the SN74 and the speedo are both getting power. So then after it's all wired up, here is the calibration process (short read): http://www.classicinstruments.com/Us...alibration.pdf
Unfortunately, when I get to 60mph using a speedometer app on my phone, hold the SN74 pushbutton down to get into Real Time calibration mode, and then click the pushbutton again, THE NEEDLE DOESN'T MOVE. I mean it doesn't move AT ALL.
Has anyone ever had experience with a Classic Instruments speedometer and an SN74 box??
I know this post is a little long but I'm not sure where to go from here. I'd call Classic's tech line, but that's the same line that told me to get the SN74 and it's not working. They're also closed on weekend which is when I have time to work on my car.
I'm so close!! One last gauge to go; thanks to anyone willing to help me out at all!
08-15-2010, 12:25 PM
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Ok, what I did just now was I took the VSS OUTPUT wire out of the Input spot on the SN74, and took the wire out of the Output spot on the SN74, and connected those two wires together. So the VSS OUTPUT wire is now directly wired to the #3 terminal on the back of my speedometer, the signal terminal.
Took it out for a drive at 60mph, and the needle DID NOT move. Brought it home, checked voltage with a multimeter at the power and ground terminals on my speedometer, and I'm getting 12.25 volts, so I know the gauge is getting power.
Anyone have any ideas?
Took it out for a drive at 60mph, and the needle DID NOT move. Brought it home, checked voltage with a multimeter at the power and ground terminals on my speedometer, and I'm getting 12.25 volts, so I know the gauge is getting power.
Anyone have any ideas?
08-15-2010, 01:07 PM
#5
Do you have access to an Ocilloscope?
First thing you need to do is make sure that the VSS signal comming from the transmission is getting to the PCM. Then from the PCM to the classic box.
My money is on the VSS either not generating the signal, or not transmitting the signal to the PCM.
First thing you need to do is make sure that the VSS signal comming from the transmission is getting to the PCM. Then from the PCM to the classic box.
My money is on the VSS either not generating the signal, or not transmitting the signal to the PCM.
08-15-2010, 01:37 PM
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Have a look at page 14 of the install manual... maybe it applies to you..hope it does.
Using a SN74 Speedometer Signal Interface
Step 1: Set the 12 dip switches on the back of the speedometer to the default setting
[5, 6, 7, 8 OPEN]
Step 2: Set the SN74 dip switch settings:
•
If using a 2-wire VSS signal, set switches 1, 2, 3, 4 OFF
•
If using an ECM signal, set switches 1,2 ON and 3,4 OFF
Step 3: Follow the procedure below to put the SN74 into the calibration mode.
1)
Start with the vehicle power / engine off. Push and hold the pushbutton then start the engine.
2)
Once the engine is running, release the pushbutton.
3)
The red LED labeled “1” on the module will be on solid (indicating real-time calibration mode).
4)
Tapping the pushbutton will cause the red LED labeled “2” on the module to turn on (indicating marked mile calibration mode).
5)
Tapping the pushbutton again will cause both red LEDS on the module to turn on (indicating reset mode).
6)
Tapping the pushbutton once again will cause the red LED labeled “1” to turn on again. Continuing to tap the pushbutton will cycle LEDS on the module through the real-time, marked mile and reset modes.
7)
Push and hold the pushbutton for approximately 5 seconds to enter the mode indicated by the red LED of the module.
Step 4: Follow the procedure below to calibrate the speedometer by driving a known mile.
1)
Push and hold the pushbutton with red LED “2” lit until LED “2” starts blinking (approximately 5 seconds)
2)
Begin driving a known mile. (The green LED on the module should blink once you start moving indicating that it is getting a signal.) When driving the known mile, the speedometer will not indicate any speed. This is normal.
3)
At the end of the known mile, press and hold the pushbutton until the red LED “2” goes off (approximately 5 seconds)
Step 5: Follow the procedure below to fine tune the speedometer calibration (if necessary).
1)
Enter the calibration mode selection as detailed in step 3.
2)
Push and hold the pushbutton with red LED “1” lit until LED “1” starts blinking. (approximately 5 seconds)
3)
Drive a known speed (use GPS or pace another car).
4)
The first time the pushbutton is pressed, the speed shown on the speedometer will increase. The second time the pushbutton is pressed, the speed shown on the speedometer will decrease.
5)
The pushbutton will alternate increasing or decreasing the speed shown on the speedometer each time it is pressed. Press and hold the pushbutton to fine tune the speed shown on the speedometer.
Using a SN74 Speedometer Signal Interface
Step 1: Set the 12 dip switches on the back of the speedometer to the default setting
[5, 6, 7, 8 OPEN]
Step 2: Set the SN74 dip switch settings:
•
If using a 2-wire VSS signal, set switches 1, 2, 3, 4 OFF
•
If using an ECM signal, set switches 1,2 ON and 3,4 OFF
Step 3: Follow the procedure below to put the SN74 into the calibration mode.
1)
Start with the vehicle power / engine off. Push and hold the pushbutton then start the engine.
2)
Once the engine is running, release the pushbutton.
3)
The red LED labeled “1” on the module will be on solid (indicating real-time calibration mode).
4)
Tapping the pushbutton will cause the red LED labeled “2” on the module to turn on (indicating marked mile calibration mode).
5)
Tapping the pushbutton again will cause both red LEDS on the module to turn on (indicating reset mode).
6)
Tapping the pushbutton once again will cause the red LED labeled “1” to turn on again. Continuing to tap the pushbutton will cycle LEDS on the module through the real-time, marked mile and reset modes.
7)
Push and hold the pushbutton for approximately 5 seconds to enter the mode indicated by the red LED of the module.
Step 4: Follow the procedure below to calibrate the speedometer by driving a known mile.
1)
Push and hold the pushbutton with red LED “2” lit until LED “2” starts blinking (approximately 5 seconds)
2)
Begin driving a known mile. (The green LED on the module should blink once you start moving indicating that it is getting a signal.) When driving the known mile, the speedometer will not indicate any speed. This is normal.
3)
At the end of the known mile, press and hold the pushbutton until the red LED “2” goes off (approximately 5 seconds)
Step 5: Follow the procedure below to fine tune the speedometer calibration (if necessary).
1)
Enter the calibration mode selection as detailed in step 3.
2)
Push and hold the pushbutton with red LED “1” lit until LED “1” starts blinking. (approximately 5 seconds)
3)
Drive a known speed (use GPS or pace another car).
4)
The first time the pushbutton is pressed, the speed shown on the speedometer will increase. The second time the pushbutton is pressed, the speed shown on the speedometer will decrease.
5)
The pushbutton will alternate increasing or decreasing the speed shown on the speedometer each time it is pressed. Press and hold the pushbutton to fine tune the speed shown on the speedometer.
08-15-2010, 01:51 PM
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Alba Gu Brath, yup, it does, and that is EXACTLY how I tried to calibrate it. But when I'm in the REAL TIME CALIBRATION mode, and the red LED is blinking red on '1', when I press the pusbutton, the needle on the gauge is SUPPOSED to go up.
But my needle doesn't move AT ALL.
I'm starting to think what Deserttaco is thinking - that I may not be getting signal to the gauge. I have the two VSS wires going from the reluctor wheel/pigtail harness on the TH400's tailshaft to the PCM, so I now I'm trying to figure out how to verify that I'm getting signal from the VSS SPEED OUTPUT wire on the PCM.
By the way, the wiring harness and PCM is a 98 - pin 55 on Red is the VSS SPEED OUTPUT (in case anyone needs that info in the future).
But my needle doesn't move AT ALL.
I'm starting to think what Deserttaco is thinking - that I may not be getting signal to the gauge. I have the two VSS wires going from the reluctor wheel/pigtail harness on the TH400's tailshaft to the PCM, so I now I'm trying to figure out how to verify that I'm getting signal from the VSS SPEED OUTPUT wire on the PCM.
By the way, the wiring harness and PCM is a 98 - pin 55 on Red is the VSS SPEED OUTPUT (in case anyone needs that info in the future).
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08-15-2010, 02:19 PM
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I'm going to head to Fry's to see what the prices are on an oscilliscope. I agree with you about signal possibly not getting from the PCM speed output wire to the gauge.
08-15-2010, 02:39 PM
#9
Don't count on that... The Fuel pressure isn't regulated by the PCM. The engine will run all day without input from the VSS. Just leave your car in neutral and rev the engine..... The Injector pulse width changes based on the RPM, Throttle position, and a bunch of other stuff. The VSS doesn't come into the picture... Read the PM I sent you and let me know what you find.
Steve
Steve
08-15-2010, 03:35 PM
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Good point, I forgot about that.
Awesome. The cheapest oscilliscope I found at Fry's was $390. That rules that out. lol
I got your pm Steve, thanks man. I will start probing around and let you know what I find.
Awesome. The cheapest oscilliscope I found at Fry's was $390. That rules that out. lol
I got your pm Steve, thanks man. I will start probing around and let you know what I find.
08-15-2010, 05:30 PM
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A friend of mine had an electric Cyberdyne gauge in his garage. I wired up the + and -, and the signal wire to the VSS speed output wire and drove the car. It read 0mph the entire time.
Either I'm not getting a signal from the PCM, or I'm not getting a signal to from the VSS on the transmission.
The hunt is on...
Either I'm not getting a signal from the PCM, or I'm not getting a signal to from the VSS on the transmission.
The hunt is on...
08-16-2010, 07:30 PM
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It works!!!! Ok, I spoke with Classic Instrument's tech line - it was a misprint in the instruction manual.
Where it says:
Step 5: Follow the procedure below to fine tune the speedometer calibration (if necessary).
1) Enter the calibration mode selection as detailed in step 3.
2) Push and hold the pushbutton with red LED “1” lit until LED “1” starts blinking. (approximately 5 seconds)
3) Drive a known speed (use GPS or pace another car).
(and here is the misprint):
4) The first time the pushbutton is pressed, the speed shown on the speedometer will increase. The second time the pushbutton is pressed, the speed shown on the speedometer will decrease.
5) The pushbutton will alternate increasing or decreasing the speed shown on the speedometer each time it is pressed. Press and hold the pushbutton to fine tune the speed shown on the speedometer.
Step 4 above SHOULD say this:
4) Then press and hold the pushbutton to make the speedometer needle move. The first time the pushbutton is pressed and held, the speed shown on the speedometer will increase. The second time the pushbutton is pressed and held, the speed shown on the speedometer will decrease.
I was just clicking the pushbutton to try and make the needle go up or down. All I had to do was press AND HOLD the button until the needle moved.
The gauge works perfectly now.
Classic Instrument's tech line had told me that if the green LED is blinking, that means I am getting a GOOD signal from the PCM's vehicle speed output wire. They also said that for my particular gauge, it was NOT designed to splice directly to a VSS wire.
Now all my gauges work; MAN I am happy. Thanks for all your help guys.
Where it says:
Step 5: Follow the procedure below to fine tune the speedometer calibration (if necessary).
1) Enter the calibration mode selection as detailed in step 3.
2) Push and hold the pushbutton with red LED “1” lit until LED “1” starts blinking. (approximately 5 seconds)
3) Drive a known speed (use GPS or pace another car).
(and here is the misprint):
4) The first time the pushbutton is pressed, the speed shown on the speedometer will increase. The second time the pushbutton is pressed, the speed shown on the speedometer will decrease.
5) The pushbutton will alternate increasing or decreasing the speed shown on the speedometer each time it is pressed. Press and hold the pushbutton to fine tune the speed shown on the speedometer.
Step 4 above SHOULD say this:
4) Then press and hold the pushbutton to make the speedometer needle move. The first time the pushbutton is pressed and held, the speed shown on the speedometer will increase. The second time the pushbutton is pressed and held, the speed shown on the speedometer will decrease.
I was just clicking the pushbutton to try and make the needle go up or down. All I had to do was press AND HOLD the button until the needle moved.
The gauge works perfectly now.
Classic Instrument's tech line had told me that if the green LED is blinking, that means I am getting a GOOD signal from the PCM's vehicle speed output wire. They also said that for my particular gauge, it was NOT designed to splice directly to a VSS wire.
Now all my gauges work; MAN I am happy. Thanks for all your help guys.
