Service ASR light on and no Tachometer, 1993 LT1 w/ DELTEQ
06-07-2007, 07:40 PM
#1
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St. Jude Donor '03 & '05
Service ASR light on and no Tachometer, 1993 LT1 w/ DELTEQ
After getting my transmission on the road again, thanks PETE K, my tachometer was intermittently on and off and my service ASR came on.
I shut her off, ran codes and recieved none. Reset the ECM, light came back on, and no tach. Then driving down the road the tach came back on, but service ASR still on. Turned off car, restarted had both tach and no service asr, till I drove up in my driveway.
So, I verified tach filter bypass of many years ago was cleaned and reconnected. Changed out TPS with known good one. Brake fluid is full, battery is charging is 13.6 volts. Engine runs fine.
Any other things to check?
I shut her off, ran codes and recieved none. Reset the ECM, light came back on, and no tach. Then driving down the road the tach came back on, but service ASR still on. Turned off car, restarted had both tach and no service asr, till I drove up in my driveway.
So, I verified tach filter bypass of many years ago was cleaned and reconnected. Changed out TPS with known good one. Brake fluid is full, battery is charging is 13.6 volts. Engine runs fine.
Any other things to check?
06-07-2007, 09:55 PM
#2
Team Owner
this is exactly a problem with the tach filter.
I don't know how the Delteq works, but the LTCC has it's own tach feed, and that hits the one of many white wires that comes out of the coil harness.
I don't know how the Delteq works, but the LTCC has it's own tach feed, and that hits the one of many white wires that comes out of the coil harness.
06-07-2007, 10:19 PM
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St. Jude Donor '03 & '05
I remember trying to get a shift light to work off of the DELTEQ. Could never get it to work. But my tach filter is bypassed. So, I am thinking it was a loose connection within the bypass job I did years ago. SO I reconnected it as I cut further down the wire to clean wire, removed the filter altogether. And hopefully with the new, well proven TPS sensor which my car has problems with every blue moon showing ASR/SERVICE ASR till restart, things will clear up.
06-07-2007, 10:37 PM
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06-08-2007, 06:52 AM
#10
Safety Car
With the Delteq, the tach signal is generated in the Northstar coil-pak and goes out through the Delteq wiring and connectors to the location of the tach-filter.
Since you have already checked and cleaned the connections at the tach filter, I suggest unplugging the Delteq connectors, clean, and replace them to see if it is a poor connection there.
By far, the best way to trouble-shoot this problem is looking at the signals with an oscilloscope to see where they are good or missing -- otherwise, you are just guessing.
If you know someone with an electronics background and has an oscilloscope, I would ask them.
The stock ignition system uses the tach filter to filter the ignition coil "dirty" signal into a reasonable "clean" square wave for the tachometer and ASR.
The Delteq (and most other multi-coil igntion systems, like the LTCC) uses the signal from the coil pak electronics.
And, this signal is already a clean square wave and does not need to be filtered -- thus, the tach filter is not necessary and shouldn't be used.
By bypassing the tach-filter, you are feeding the clean square wave directly to the ECM for a tach signal.
Tom Piper
Since you have already checked and cleaned the connections at the tach filter, I suggest unplugging the Delteq connectors, clean, and replace them to see if it is a poor connection there.
By far, the best way to trouble-shoot this problem is looking at the signals with an oscilloscope to see where they are good or missing -- otherwise, you are just guessing.
If you know someone with an electronics background and has an oscilloscope, I would ask them.
The stock ignition system uses the tach filter to filter the ignition coil "dirty" signal into a reasonable "clean" square wave for the tachometer and ASR.
The Delteq (and most other multi-coil igntion systems, like the LTCC) uses the signal from the coil pak electronics.
And, this signal is already a clean square wave and does not need to be filtered -- thus, the tach filter is not necessary and shouldn't be used.
By bypassing the tach-filter, you are feeding the clean square wave directly to the ECM for a tach signal.
Tom Piper
Last edited by Tom Piper; 06-08-2007 at 07:24 AM.
06-08-2007, 02:57 PM
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St. Jude Donor '03 & '05
With the Delteq, the tach signal is generated in the Northstar coil-pak and goes out through the Delteq wiring and connectors to the location of the tach-filter.
Since you have already checked and cleaned the connections at the tach filter, I suggest unplugging the Delteq connectors, clean, and replace them to see if it is a poor connection there.
By far, the best way to trouble-shoot this problem is looking at the signals with an oscilloscope to see where they are good or missing -- otherwise, you are just guessing.
If you know someone with an electronics background and has an oscilloscope, I would ask them.
The stock ignition system uses the tach filter to filter the ignition coil "dirty" signal into a reasonable "clean" square wave for the tachometer and ASR.
The Delteq (and most other multi-coil igntion systems, like the LTCC) uses the signal from the coil pak electronics.
And, this signal is already a clean square wave and does not need to be filtered -- thus, the tach filter is not necessary and shouldn't be used.
By bypassing the tach-filter, you are feeding the clean square wave directly to the ECM for a tach signal.
Tom Piper
Since you have already checked and cleaned the connections at the tach filter, I suggest unplugging the Delteq connectors, clean, and replace them to see if it is a poor connection there.
By far, the best way to trouble-shoot this problem is looking at the signals with an oscilloscope to see where they are good or missing -- otherwise, you are just guessing.
If you know someone with an electronics background and has an oscilloscope, I would ask them.
The stock ignition system uses the tach filter to filter the ignition coil "dirty" signal into a reasonable "clean" square wave for the tachometer and ASR.
The Delteq (and most other multi-coil igntion systems, like the LTCC) uses the signal from the coil pak electronics.
And, this signal is already a clean square wave and does not need to be filtered -- thus, the tach filter is not necessary and shouldn't be used.
By bypassing the tach-filter, you are feeding the clean square wave directly to the ECM for a tach signal.
Tom Piper
I have dealt with O-scopes for about 19 years, and I can understand using one to find this issue. But right now I am doing what the basic person needs to do, ask, clean and inspect and reconnect. If this fails, I will get her done at work with an O-Scope and see what signal is being dropped intermittenly. Thanks
06-08-2007, 11:17 PM
#12
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St. Jude Donor '03 & '05
Well I drove it for about 50 miles, which is almost one end of the island to the other, and no service ASR, and the tachometer worked. So, by cleaning the connectors, replaceing the TPS switch and cleaning its connectors and removing tach filter altogether, one of these fixed it. I think the tach filter and its wires being old were the culprit.
