Error 1797 ????
#61
05-31-2017, 04:09 AM
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mgman71 (06-01-2017)
#62
06-01-2017, 09:05 AM
It fails NYS inspection when they plug in there computer it fails there is no way around it. I am been in contact with NYSDMV they are no help they say its has to pass on there system or no go. The code come up on my scanner when I do a TCM scan and it fails with a 1797 I do a ECM scan no errors....
Last edited by mgman71; 06-01-2017 at 05:02 PM.
#63
06-01-2017, 09:13 AM
Hi George,
From your description I take it that you visually inspected the connector pins but did not flush them with zero-residue electrical contact cleaner or clean them with a small brass-bristle brush? It's always a good idea to do that when you have connectors apart since even a thin coat of oil or the lightest coat of corrosion can introduce electrical resistance that can negatively impact these sensitive electronic circuits.
Also, as I suggested back in post #34, while you have the connectors apart you should check the CAN wires for continuity between the ECM and TCM connectors and also check both wires for shorts to ground. These tests are easy with an inexpensive volt/ohm meter (VOM) or digital volt/ohm meter (DVOM). Set the meter to measure the lowest range of resistance (typically 200 ohms unless the meter is auto-ranging, in which case you just set it to ohms or Ω). There should be continuity (very low resistance of a few ohms or less) between the terminal for the Yellow CAN wire at the ECM connector and the equivalent Yellow wire terminal at the TCM connector. The same should be true for the Green wire. Looking at the schematic in the Electrical Guide, there should be no continuity whatsoever between either wire and body ground.
One other thought that I can't recall if anyone has mentioned: It might be worth cleaning the electrical connector
at the transmission itself, since one listed possible cause of P1797 is "TCM/Control Valve Failure."
Cheers,
Don
From your description I take it that you visually inspected the connector pins but did not flush them with zero-residue electrical contact cleaner or clean them with a small brass-bristle brush? It's always a good idea to do that when you have connectors apart since even a thin coat of oil or the lightest coat of corrosion can introduce electrical resistance that can negatively impact these sensitive electronic circuits.
Also, as I suggested back in post #34, while you have the connectors apart you should check the CAN wires for continuity between the ECM and TCM connectors and also check both wires for shorts to ground. These tests are easy with an inexpensive volt/ohm meter (VOM) or digital volt/ohm meter (DVOM). Set the meter to measure the lowest range of resistance (typically 200 ohms unless the meter is auto-ranging, in which case you just set it to ohms or Ω). There should be continuity (very low resistance of a few ohms or less) between the terminal for the Yellow CAN wire at the ECM connector and the equivalent Yellow wire terminal at the TCM connector. The same should be true for the Green wire. Looking at the schematic in the Electrical Guide, there should be no continuity whatsoever between either wire and body ground.
One other thought that I can't recall if anyone has mentioned: It might be worth cleaning the electrical connector
at the transmission itself, since one listed possible cause of P1797 is "TCM/Control Valve Failure."
Cheers,
Don
Last edited by mgman71; 06-01-2017 at 05:03 PM.
#64
06-01-2017, 06:03 PM
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Hi George,
The 60 ohm measurement across the CAN yellow and green wires proves continuity all the way through at the time you measured it. You could still have an intermittent connection.
I've attached a section of the pinpoint guide which shows some of the tests that Don B has suggested. These are all done from the diagnostic connector, so they will apply to your car.
I would still follow the CAN wiring through its travels as suggested previously.
Don't lose heart: it's a process of elimination. Although it can be infuriating, each check you make that doesn't show a problem is an item you can tick off the list.
Mike
The 60 ohm measurement across the CAN yellow and green wires proves continuity all the way through at the time you measured it. You could still have an intermittent connection.
I've attached a section of the pinpoint guide which shows some of the tests that Don B has suggested. These are all done from the diagnostic connector, so they will apply to your car.
I would still follow the CAN wiring through its travels as suggested previously.
Don't lose heart: it's a process of elimination. Although it can be infuriating, each check you make that doesn't show a problem is an item you can tick off the list.
Mike
Last edited by michaelh; 06-01-2017 at 06:06 PM.
#65
06-01-2017, 06:53 PM
Hi George,
The 60 ohm measurement across the CAN yellow and green wires proves continuity all the way through at the time you measured it. You could still have an intermittent connection.
I've attached a section of the pinpoint guide which shows some of the tests that Don B has suggested. These are all done from the diagnostic connector, so they will apply to your car.
I would still follow the CAN wiring through its travels as suggested previously.
Don't lose heart: it's a process of elimination. Although it can be infuriating, each check you make that doesn't show a problem is an item you can tick off the list.
Mike
The 60 ohm measurement across the CAN yellow and green wires proves continuity all the way through at the time you measured it. You could still have an intermittent connection.
I've attached a section of the pinpoint guide which shows some of the tests that Don B has suggested. These are all done from the diagnostic connector, so they will apply to your car.
I would still follow the CAN wiring through its travels as suggested previously.
Don't lose heart: it's a process of elimination. Although it can be infuriating, each check you make that doesn't show a problem is an item you can tick off the list.
Mike
#66
06-01-2017, 07:56 PM
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Don I did remove and clean the connections and put on dielectric grease. I did a test on the CAN bus on the DLC pins 6 & 14 it was 60 ohms. I was told that checks the whole CAN bus? I will be back at the car this weekend and I will check the connector on the trans I will clean it and put on the grease.
I do use dielectric grease to the outsides of the smaller half of electrical connector housings to help seal out water and oil, but I recommend that you not put dielectric grease on connector pins of sensitive electronic circuits such as sensors and electronic control modules.
By definition, dielectric grease is an insulator that can store a static electric charge. It's fine for the bases of light bulbs that operate on a steady 12 volts and relatively high current and where just enough grease is scraped away when the bulb is fitted that a mostly metal-to-metal connection is made at the critical contact points. But for circuits that depend on the accurate transmittal of very low voltages, currents and resistances, adding any resistance at all to the connection can throw off the system readings and interfere with proper operation.
My two cents.
Cheers,
Don
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mgman71 (06-01-2017)
#67
06-01-2017, 10:14 PM
Hi George,
I do use dielectric grease to the outsides of the smaller half of electrical connector housings to help seal out water and oil, but I recommend that you not put dielectric grease on connector pins of sensitive electronic circuits such as sensors and electronic control modules.
By definition, dielectric grease is an insulator that can store a static electric charge. It's fine for the bases of light bulbs that operate on a steady 12 volts and relatively high current and where just enough grease is scraped away when the bulb is fitted that a mostly metal-to-metal connection is made at the critical contact points. But for circuits that depend on the accurate transmittal of very low voltages, currents and resistances, adding any resistance at all to the connection can throw off the system readings and interfere with proper operation.
My two cents.
Cheers,
Don
I do use dielectric grease to the outsides of the smaller half of electrical connector housings to help seal out water and oil, but I recommend that you not put dielectric grease on connector pins of sensitive electronic circuits such as sensors and electronic control modules.
By definition, dielectric grease is an insulator that can store a static electric charge. It's fine for the bases of light bulbs that operate on a steady 12 volts and relatively high current and where just enough grease is scraped away when the bulb is fitted that a mostly metal-to-metal connection is made at the critical contact points. But for circuits that depend on the accurate transmittal of very low voltages, currents and resistances, adding any resistance at all to the connection can throw off the system readings and interfere with proper operation.
My two cents.
Cheers,
Don
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Don B (06-01-2017)
#68
06-01-2017, 11:40 PM
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On what sorts of connections do you use dielectric grease in a mainframe and what is the purpose of using it?
Cheers,
Don
#69
06-02-2017, 01:20 AM
Veteran Member
Something is inconsistent. If the MIL is off there's no current code so that is not why it would fail an inspection (unless MIL has been faked in some way).
Two alternatives spring to mind:
1. there's a DLC (OBD connector) problem - bad earth, bent pin, etc
2. the inspection tests the "readiness" (OBD monitors being set) - you can read these and check them
#1 is actually possible because some OBD tools use the signals a little differently (well, wrongly) so tool A may be happy but tool B unhappy and B could be the inspection one I suppose. Unlikely but hey.
60 ohms looks good.
Two alternatives spring to mind:
1. there's a DLC (OBD connector) problem - bad earth, bent pin, etc
2. the inspection tests the "readiness" (OBD monitors being set) - you can read these and check them
#1 is actually possible because some OBD tools use the signals a little differently (well, wrongly) so tool A may be happy but tool B unhappy and B could be the inspection one I suppose. Unlikely but hey.
60 ohms looks good.
#70
06-02-2017, 08:00 AM
Don we use it on all the connectors within the main frame the use is to keep all moisture out. This is what we are told to do from development . George ( the dielectric we use is in a spray form )
Last edited by mgman71; 06-02-2017 at 08:06 AM.
#71
06-02-2017, 12:09 PM
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Thanks!
Don
#73
06-03-2017, 08:08 PM
update.. I drove the car for about 75 miles at all types of speeds. I took it to the inspection station...There were no lights on or errors on the dash and the car ran great. here are the results of the test..diagnostic trouble codes were 1797, Emissions results(MIL commanded Fail),readiness(fail),monitor catalyst , EVAP,& O2 were not ready. I am going to try to clean the transmission connector next and see if that does anything... will let you know how that does when I get it done. Thanks again for all your help... George
#74
06-04-2017, 02:48 AM
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I don't know how the system works in the US but are you taking the car to the same test station each time, and is there an alternative test station within a sensible distance.
I know it's unlikely, but your symptoms are very unusual, and I guess it is **just** possible there's some sort of incompatibility between your car and the kit in the test station.
(I failed the UK roadworthy/safety test a couple of months ago, and was just about to start taking the oxygen sensors out when the Test Station rang to say that they had discovered a problem with their computer, and to disregard the results so those sorts of thing can occasionally happen.)
I know it's unlikely, but your symptoms are very unusual, and I guess it is **just** possible there's some sort of incompatibility between your car and the kit in the test station.
(I failed the UK roadworthy/safety test a couple of months ago, and was just about to start taking the oxygen sensors out when the Test Station rang to say that they had discovered a problem with their computer, and to disregard the results so those sorts of thing can occasionally happen.)
#75
06-04-2017, 09:32 AM
I don't know how the system works in the US but are you taking the car to the same test station each time, and is there an alternative test station within a sensible distance.
I know it's unlikely, but your symptoms are very unusual, and I guess it is **just** possible there's some sort of incompatibility between your car and the kit in the test station.
(I failed the UK roadworthy/safety test a couple of months ago, and was just about to start taking the oxygen sensors out when the Test Station rang to say that they had discovered a problem with their computer, and to disregard the results so those sorts of thing can occasionally happen.)
I know it's unlikely, but your symptoms are very unusual, and I guess it is **just** possible there's some sort of incompatibility between your car and the kit in the test station.
(I failed the UK roadworthy/safety test a couple of months ago, and was just about to start taking the oxygen sensors out when the Test Station rang to say that they had discovered a problem with their computer, and to disregard the results so those sorts of thing can occasionally happen.)
#76
06-04-2017, 09:49 AM
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#77
06-08-2017, 03:19 PM
Hi David. I cleaned the plug on the Transmission ran the car for a while no errors that I can see brought it to the shop they plugged in there scanner and after a while it said no connection???... so no inspection. Not sure what to do next??? I will try another shop next week and see how it goes. Not sure how I will get there with out being inspected I know with my luck I will get stopped. Thanks again for all your input and to the group...it may be the end of the line for the car....thks George
#78
06-08-2017, 04:03 PM
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You need to find out the exceptions for emissions in your state, if it comes down to that. Your state's DMV/MVA web site would have all of that. Sometimes, you can provide documentation you spent some money, and get a waiver. Also, some inspections stations have the old rollers and sniffers (pre-OBDII), as an alternative to just a computer-based inspection. As long as you do not pollute (as measured), you should pass. It varies by state, play the game...
Best of luck, keep us posted.
Best of luck, keep us posted.
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mgman71 (06-12-2017)
#79
06-08-2017, 05:17 PM
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George, did you ever get to checking the connectors on the main dash instrument pack? They're accessible once the veneer panel is removed.
Disconnect the battery first.
Since you lay it up for the winter, I presume that the car isn't needed as a daily driver and that you can take as long as it needs to work through this?
Disconnect the battery first.
Since you lay it up for the winter, I presume that the car isn't needed as a daily driver and that you can take as long as it needs to work through this?
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mgman71 (06-12-2017)
#80
06-12-2017, 09:22 AM
George, did you ever get to checking the connectors on the main dash instrument pack? They're accessible once the veneer panel is removed.
Disconnect the battery first.
Since you lay it up for the winter, I presume that the car isn't needed as a daily driver and that you can take as long as it needs to work through this?
Disconnect the battery first.
Since you lay it up for the winter, I presume that the car isn't needed as a daily driver and that you can take as long as it needs to work through this?