Who's in control here?
06-29-2002, 01:47 PM
#1
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Who's in control here?
What is the controlling device in the world of mileage/mph?
I always thought, right or wrong, that if the odometer went 'down' my speedo wouldn't work.
But after a year of intermittent speedo operation I am starting to believe the reverse is true... speedometer 'down' = odometer 'down'.
Checked the speedo sender - cleaned, tightened loose wiring nut -, soldered in a waterproof, rubberized, 4 pin connector in the tire well. I'm thinking a new board is in order when I pull the pod. BTW Who is the Guy who posted the "just clean the board contacts by cleaning with a pencil eraser"? Please send pictures of your hands - do they resemble E.T.'s? I'll bet that light on the fingertip dealie comes in handy!
Snow, don't even say it!!
It's really nice to drive 1500 miles and only put 286 miles on the clock but it can be a bummer come belt retentioning time.
What's the relationship between the odo and speedo?
TIA
John S and Pattycakes
I always thought, right or wrong, that if the odometer went 'down' my speedo wouldn't work.
But after a year of intermittent speedo operation I am starting to believe the reverse is true... speedometer 'down' = odometer 'down'.
Checked the speedo sender - cleaned, tightened loose wiring nut -, soldered in a waterproof, rubberized, 4 pin connector in the tire well. I'm thinking a new board is in order when I pull the pod. BTW Who is the Guy who posted the "just clean the board contacts by cleaning with a pencil eraser"? Please send pictures of your hands - do they resemble E.T.'s? I'll bet that light on the fingertip dealie comes in handy!
Snow, don't even say it!!
It's really nice to drive 1500 miles and only put 286 miles on the clock but it can be a bummer come belt retentioning time.
What's the relationship between the odo and speedo?
TIA
John S and Pattycakes
06-29-2002, 01:53 PM
#2
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The speedometer and odometer are independent devices in a common housing, fed by a common input.
No signal in, neither works. Good signal in, broken orange gear, speedometer works, odo doesn't - this is a common failure.
No signal in, neither works. Good signal in, broken orange gear, speedometer works, odo doesn't - this is a common failure.
06-29-2002, 03:12 PM
#3
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Thread Starter
Thanks Wally,
I was browsing the archives when I came across your reply to a back-up harness problem, good stuff! Dennis wilson, check it out!
For clarification... the sending unit on the transmission signals, both, speedo and tach?
The orange gear is refering to the little bugger in the odometer probably related to reset on the trip meter?
In you experience, the odometer would or would not affect the the speedo- bouncing/pegging needle?
My tach is a happy camper but the speedo needle will bounce, then peg if I go over 80mph. Also,
if I romp on it and attack the 70mph barrier the speedo goes straight to peg. In your experience, does this sound like a board problem or a sending unit problem?
I soldered in a new connector - orig. post - so I think we can eliminate that as a problem.
TIA
John S. & Pattycakes <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" /> 
I was browsing the archives when I came across your reply to a back-up harness problem, good stuff! Dennis wilson, check it out!
For clarification... the sending unit on the transmission signals, both, speedo and tach?
The orange gear is refering to the little bugger in the odometer probably related to reset on the trip meter?
In you experience, the odometer would or would not affect the the speedo- bouncing/pegging needle?
My tach is a happy camper but the speedo needle will bounce, then peg if I go over 80mph. Also,
if I romp on it and attack the 70mph barrier the speedo goes straight to peg. In your experience, does this sound like a board problem or a sending unit problem?
I soldered in a new connector - orig. post - so I think we can eliminate that as a problem.
TIA
John S. & Pattycakes
<img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />
06-29-2002, 03:38 PM
#4
The sending unit on the transmission does provide the signal for both the tach and speedometer.
The orange gear is the one in the odometer, and it may or may not be messed up due to resetting the trip odometer.
The odometer should not have anything to do with the strange speedometer behavior.
The speedometer problem sounds most like a connection problem at the board or elsewhere. The sending unit works by picking up pulses from a ring with magnets that spins inside the transmission. It's just a Hall effect device, and should generally be pretty reliable. The latest cars used the signal from the ABS sensors instead of the ring with magnets in the transmission method.
The orange gear is the one in the odometer, and it may or may not be messed up due to resetting the trip odometer.
The odometer should not have anything to do with the strange speedometer behavior.
The speedometer problem sounds most like a connection problem at the board or elsewhere. The sending unit works by picking up pulses from a ring with magnets that spins inside the transmission. It's just a Hall effect device, and should generally be pretty reliable. The latest cars used the signal from the ABS sensors instead of the ring with magnets in the transmission method.
06-29-2002, 03:43 PM
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Hey John! If everything quits, it is a systemic problem, like a bad motor that controls BOTH the odometer AND the speedometer, or a lack of proper current. Both are controlled by the same motor, but after the motor, they have seperate gears that control them seperately. So, the gear that connects the motor to the odometer is old/broken/subluxated. So, open it up and look at how the gears condition and position are between the motor and the odometer. Just be careful with the speedo needle....they are very fragile....and don't loose the screws that hold the speedometer face on :-) from your fellow Weissach owner!
06-29-2002, 03:50 PM
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John,
I couldn't find the archive your talking about from Wally. How can I find it ? Would like to read that. I am still having problems with my tach.
John D.
'85 928 Auto, Black
I couldn't find the archive your talking about from Wally. How can I find it ? Would like to read that. I am still having problems with my tach.
John D.
'85 928 Auto, Black
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06-29-2002, 04:41 PM
#8
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Thread Starter
Doz,
Go to top of the page click page 9, scroll down it should be right before the post on John B's engine swap.
We are talking about the back -up harness here, Right?
Imbedded in the quetion was a query as to what some of the switches and sending unit's sprouted off of the Tranny, O.K.?
John.S <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
Go to top of the page click page 9, scroll down it should be right before the post on John B's engine swap.
We are talking about the back -up harness here, Right?
Imbedded in the quetion was a query as to what some of the switches and sending unit's sprouted off of the Tranny, O.K.?
John.S <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
06-29-2002, 08:22 PM
#10
John,
Thanks for the tip. I received a new reverse light switch yesterday. That should fix the backup light problem if I can remember to put the fuse back in.
Thanks,
Dennis
Thanks for the tip. I received a new reverse light switch yesterday. That should fix the backup light problem if I can remember to put the fuse back in.
Thanks,
Dennis
06-30-2002, 12:02 PM
#11
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The electronic sensor on the differential cover only serves the speedometer, its not a tach input.
The tach signal is from the ignition-timing sensor (rear of engine black). Not to be confused with the TDC (top dead center sensor, test sensor) on the engine bell housing. The ignition-timing sensor has a duel function. It serves as a reference for engine speed (RPM) and crank position sensor (for timing). The tack input signal is generated from the EZK controller via the ignition-timing sensor, on later vehicles. On the early 928’s the tach signal is form the ignition control unit. Pin # 8 tach feed wire.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
The tach signal is from the ignition-timing sensor (rear of engine black). Not to be confused with the TDC (top dead center sensor, test sensor) on the engine bell housing. The ignition-timing sensor has a duel function. It serves as a reference for engine speed (RPM) and crank position sensor (for timing). The tack input signal is generated from the EZK controller via the ignition-timing sensor, on later vehicles. On the early 928’s the tach signal is form the ignition control unit. Pin # 8 tach feed wire.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
06-30-2002, 12:58 PM
#12
[quote]Originally posted by Mike Schmidt:
<strong>The sending unit on the transmission does provide the signal for both the tach and speedometer.</strong><hr></blockquote>
Ooops. What I meant to say was that it sends the signal for the speedometer and ODOMETER, not the tachometer. As Steve said, the tachometer signal is a whole different thing.
<strong>The sending unit on the transmission does provide the signal for both the tach and speedometer.</strong><hr></blockquote>
Ooops. What I meant to say was that it sends the signal for the speedometer and ODOMETER, not the tachometer. As Steve said, the tachometer signal is a whole different thing.
06-30-2002, 05:13 PM
#13
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Mike,
Caught it, thanks. But then promptly bum-steered Doz ...just thinking of the archive location and not content. <img src="graemlins/oops.gif" border="0" alt="[oops]" />
Doz,
Sorry!!!
May have some help with the following question.
Steve,
Thanks much...
A question, if I may?
Is there an amplifier for either the speedo, or, tach.? If so, where does it, they live?
TIA
Snow,
I thought Al only takes over after a lung shot...
Anyway he's the point man for the Army of One.
Iraq or bust...you'd like him he's like the rest of those Talking Heads on Fox - better a million dead Arabs than a one penny raise -or less- in gas pricing. What can we blame them for, today?
Terroristic breathing with felony intent to survive? Yuk, yuk, yuk, hey Moe!
John S.
Caught it, thanks. But then promptly bum-steered Doz ...just thinking of the archive location and not content. <img src="graemlins/oops.gif" border="0" alt="[oops]" />
Doz,
Sorry!!!
May have some help with the following question.
Steve,
Thanks much...
A question, if I may?
Is there an amplifier for either the speedo, or, tach.? If so, where does it, they live?
TIA
Snow,
I thought Al only takes over after a lung shot...
Anyway he's the point man for the Army of One.
Iraq or bust...you'd like him he's like the rest of those Talking Heads on Fox - better a million dead Arabs than a one penny raise -or less- in gas pricing. What can we blame them for, today?
Terroristic breathing with felony intent to survive? Yuk, yuk, yuk, hey Moe!
John S.
06-30-2002, 10:14 PM
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John,
The tech input signal on your car originates from the distributor. The transistor ignition control unit processes it.
The speedometer signal is processes by a solid-state circuit in the mileage counter (speedometer head-). If your odometer is not working it probably has a striped gear.
On Dozmen car the AC signal from the RPM and reference mark transmitter (magnetic inductive sensor), Is fed into the EZF controller, there the AC signal is converted into a digital signal.
If Dozman were having a problem with his tech I would change the RPM, Rm sensor. It’s a magnetic sensor. When the magnet gets weak it affects the signal, the only way to check it is with an oscilloscope. If the tech still doesn’t work with a new sensor substitute the EZF controller with a good donor one. If he has access to an oscilloscope, connect the positive lead to terminal # 7, and negative lead to terminal #19 of the disconnect EZF control plug. You should see a sine wave oscillation of at least 2.5 volts.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
The tech input signal on your car originates from the distributor. The transistor ignition control unit processes it.
The speedometer signal is processes by a solid-state circuit in the mileage counter (speedometer head-). If your odometer is not working it probably has a striped gear.
On Dozmen car the AC signal from the RPM and reference mark transmitter (magnetic inductive sensor), Is fed into the EZF controller, there the AC signal is converted into a digital signal.
If Dozman were having a problem with his tech I would change the RPM, Rm sensor. It’s a magnetic sensor. When the magnet gets weak it affects the signal, the only way to check it is with an oscilloscope. If the tech still doesn’t work with a new sensor substitute the EZF controller with a good donor one. If he has access to an oscilloscope, connect the positive lead to terminal # 7, and negative lead to terminal #19 of the disconnect EZF control plug. You should see a sine wave oscillation of at least 2.5 volts.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />