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Ign module tach wire


ChrisWhewell
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For posterity's sake, the solution to this was changing out the ECM.

 

Note to self:  If changing the ECM in the future, after unplugging the three connectors, move all three to the right as much as possible.  Disconnect the antenna wire coupling and the white connector that is also in the way.  Loosen and remove the 10mm bolt that is over to the left a little, that holds a wad of vacuum hoses in place.  Remove floor mat.  Remove the single torx fastener that holds the ECM in place and pull it out.  When replacing, push the wire harness with the three connectors over to the right and out of the way.  This is a 10 minute job.

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  • 5 years later...
On 7/11/2016 at 3:20 PM, KDirk said:

If you enter diagnostics, and pull parameter ED11 (ecm data #11) that is the raw tach data. I suspect you have an ICM failure as well since you have the green slime evident, and perhaps it is not reporting the tach data to the ECM and in turn the BCM cannot add the tach data to the data stream it sends to the IPC for interpretation and display. If ED11 shows 0 with the engine running while in diagnostics then the cluster isn't getting the tach data to begin with. 

 

Then again, you are losing the temp gauge as well. That does not get reported by the ICM but the engine temp sensor which has a direct input to the ECM. That makes me think you may have an IPC (or less likely a BCM) problem that is  causing it to drop the tach and temp data. I can't see a situation where loss of tach data would affect the display of the temp gauge. Keep in mind that all the data displayed on  the cluster is "picked off" a continuous serial formatted data stream that contains the vehicle speed, engine RPM, temp, fuel level, voltage, both the total and trip odometers as well as the state of the various status and malfunction indicators (lights on, SES, electrical problem, ABS, service A/C, headlamps suggested etc.).

 

It is possible for one or more parameters to be missing form the data stream due to a failed sensor, bad wiring, or even a malfunctioning module.  I guess my point is that you may have a bad ICM but there may be another fault present as I don't see the ICM problem being relevant or related to the loss of temperature gauge readout.

 

 

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On 7/19/2016 at 7:58 PM, ChrisWhewell said:

 

So, I go into diagnostic mode, to read data for ED01, ED04, ED06, etc.   I got up to ED11 (eng. speed) and it read correctly, but just then at that moment, the tachometer crapped out, the diagnostic mode reset itself back to square 1, and when I got it back around to where it read:  "EC ?" and I entered "yes" (up arrow), the message it gave was "no Ec data".  Cannot get any Ec data while the tachometer is not reading anything.  Only when the tach display is active am I able to see any Ec diagnostic values.     Its starting to sound that I don't have a bad IPC, rather an ECM with an intermittent failure, in the circuit that sends tach info to the IPC.   

 

There is also a b334 code, indicating loss of ECM communication, but it is intermittent as well.   I've already pulled the three connectors from the ECM, sprayed them with CRC followed by blasts of compressed air.   Its sounding as though I need to start hunting down an ECM...  ??

 

 

 

 

 

 

Hi Chris my 1991 Buick Riviera temp gauge goes out after car reaches normal driving temperature digital dash driving me nuts

 

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  • 2 weeks later...
On 5/23/2022 at 4:12 PM, padgett said:

OY The Reatta has a built in diagnostic (scan tool). See here. Is also in the factory service manual. Every car out of warranty should have one.

Padgett you may want to look at this a bit closer for Autry. I have never seen his issue and will try explaining it to you as I understand it.

He has a 1991 Riviera. What happens is he will be driving along when all of a sudden the blocks that show the cars temperature "disappear" leaving only the temperature lines on the IPC. All other gauges continue to read as they should. At this point the car goes into "cripple" mode and the AC gets turned off. 

He has also noticed a "clicking" noise behind the glove compartment which I believe is the ECM making adjustments to the vents. 

Is there a test he can run or is there something wrong with the ECM? 

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10 hours ago, DAVES89 said:

Padgett you may want to look at this a bit closer for Autry. I have never seen his issue and will try explaining it to you as I understand it.

He has a 1991 Riviera. What happens is he will be driving along when all of a sudden the blocks that show the cars temperature "disappear" leaving only the temperature lines on the IPC. All other gauges continue to read as they should. At this point the car goes into "cripple" mode and the AC gets turned off. 

He has also noticed a "clicking" noise behind the glove compartment which I believe is the ECM making adjustments to the vents. 

Is there a test he can run or is there something wrong with the ECM? 

Hi Dave my mechanic told me the wire that goes to the ecm when touched it shorten out the bars on the temp display so I ordered a ecm and c if it works thks

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On 5/21/2022 at 2:10 PM, padgett said:

Have you checked ED04 to see if the sensor has been lost or the display ?

Hi Padgett this is Autry I had my mechanic research in 1991 Haynes manual for Buick Riviera. He said the wire that goes to the ecm when touch shortens out the temp display bars on the digital dash he kept the car for 4 days and told me to order a ecm so I'll c if that works

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"a "clicking" noise behind the glove compartment " - HVAC programmed has relays & BCM is close. ECM is essentially in footwell. ED04 is the ECM reading from the temp sensor. If it is matching the gauge the sensor or wiring has a problem. If has a steady reading it is the ECM,  IPC, or wiring but doubt that because the dash runs off the ALDL serial link and would affect more than the temp gauge.

 

Jim probably has a '91 ECM but probably need to use your PROM. Not sure if the Haynes has as much detail on the ALDL LAN as the FSM.

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  • 3 weeks later...

I replaced ecm and that fixed it

On 6/4/2022 at 11:28 PM, padgett said:

"a "clicking" noise behind the glove compartment " - HVAC programmed has relays & BCM is close. ECM is essentially in footwell. ED04 is the ECM reading from the temp sensor. If it is matching the gauge the sensor or wiring has a problem. If has a steady reading it is the ECM,  IPC, or wiring but doubt that because the dash runs off the ALDL serial link and would affect more than the temp gauge.

 

Jim probably has a '91 ECM but probably need to use your PROM. Not sure if the Haynes has as much detail on the ALDL LAN as the FSM.

 

On 6/4/2022 at 11:28 PM, padgett said:

"a "clicking" noise behind the glove compartment " - HVAC programmed has relays & BCM is close. ECM is essentially in footwell. ED04 is the ECM reading from the temp sensor. If it is matching the gauge the sensor or wiring has a problem. If has a steady reading it is the ECM,  IPC, or wiring but doubt that because the dash runs off the ALDL serial link and would affect more than the temp gauge.

 

Jim probably has a '91 ECM but probably need to use your PROM. Not sure if the Haynes has as much detail on the ALDL LAN as the FSM.

 

On 5/19/2022 at 7:27 PM, Autry said:

I replaced ecm now good 

 

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On 10/10/2016 at 10:40 AM, ChrisWhewell said:

For posterity's sake, the solution to this was changing out the ECM.

 

Note to self:  If changing the ECM in the future, after unplugging the three connectors, move all three to the right as much as possible.  Disconnect the antenna wire coupling and the white connector that is also in the way.  Loosen and remove the 10mm bolt that is over to the left a little, that holds a wad of vacuum hoses in place.  Remove floor mat.  Remove the single torx fastener that holds the ECM in place and pull it out.  When replacing, push the wire harness with the three connectors over to the right and out of the way.  This is a 10 minute job.

I replaced the ecm now all good 👍

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On 6/4/2022 at 5:28 PM, Autry said:

Hi Dave my mechanic told me the wire that goes to the ecm when touched it shorten out the bars on the temp display so I ordered a ecm and c if it works thks

Replaced ecm now all g 👍

On 10/10/2016 at 10:40 AM, ChrisWhewell said:

For posterity's sake, the solution to this was changing out the ECM.

 

Note to self:  If changing the ECM in the future, after unplugging the three connectors, move all three to the right as much as possible.  Disconnect the antenna wire coupling and the white connector that is also in the way.  Loosen and remove the 10mm bolt that is over to the left a little, that holds a wad of vacuum hoses in place.  Remove floor mat.  Remove the single torx fastener that holds the ECM in place and pull it out.  When replacing, push the wire harness with the three connectors over to the right and out of the way.  This is a 10 minute job.

I replaced the ecm now all good 👍

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