Question about 1991 Buick Riviera

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Do you know where I can purchase or have any advice to repair an 1991 computer ECM prom or component? I have a computer code readout of #47

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My advice would be to find a junkyard somewhere near to you.

Posted on Jan 06, 2009


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Posted on Jan 02, 2017


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We had a dodge dakota with the same symptoms and they found a corroded pin on the main connector to the ecm . I think P1682 is low voltage from the charging system. Hope this might help.

Mar 13, 2014 | 2005 GMC Envoy

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87 Buick century...3.8 well maintained...had in garage for a month...all sensors have been verified..bought new computer and used old proms..still no resolve...finally took to dealer and they said a bad...

I doubt the ECM from a C body would work on your Century. I would probably buy a used computer and prom from a car exactly like yours. The prom is calibrated to the body style, engine, and trans. Each year and model can be different due to emissions standards.

Jul 11, 2013 | Cars & Trucks

2 Answers

Fuel/spark problelms with 1991 buick lesabre

Sounds like the timing is too low - if it is electronic timing id check the computer with a code scanner - something not quite right tho... but you dont want to spend good money after bad but.... that can be a bottomless pit!

May 06, 2017 | 1991 Buick LeSabre

2 Answers

Where is the ECM located


The ECM is mounted on the right side of the dash above where the passengers feet would be.
The lower panel will need to be removed to see it.
Here is the service manual procedure to remove it.
  1. Turn ignition to "OFF".
  2. Disconnect battery ground cable.
  3. Remove right hand hush panel.
  4. Disconnect connectors from the ECM
  5. Remove ECM mounting hardware.
  6. Remove ECM from the passenger compartment.
  7. Remove ECM access cover.
  8. Transfer PROM unit to replacement ECM. Using two fingers, push both retaining clips back away from the PROM. At the same time, grasp it at both ends and lift it up out of the socket. Do not remove the cover of the PROM. Use of unapproved PROM removal methods may cause damage to the PROM or socket.
  9. Remove new ECM from its packaging and check the service number to make sure it is the same as the defective ECM.
  10. Remove access cover.

There you are. I hope your repair goes well.


Jan 12, 2011 | 1992 Buick Century

1 Answer

If I change the ecm, does it need to be programmed? I'm purchasing a new one from a local parts store and have never done one.

Late 95 into 96 is when the changed from an ecm that had a replaceable (prom) to one that was made into the computer that would have to be programmed.Check you original ecm for a plate covering a removeable prom if it has one swap it into the new one and your good to go If not you will need to get the new one programmed

Sep 08, 2010 | 1995 Buick Park Avenue

1 Answer

This car runs for approximately 10 minutes then shuts off. We have replaced the ignition module and fuel pump but it still does the same thing. What else could it be?

The only thing that it would most likely be (if not the ignition module, the fuel pump, a faulty fuel pump relay if applicable, or a faulty ignition coil pack but only if one coil pack is used, and if more than one coil pack they would all have to be faulty to shut down the engine) is the ECM/ECC, especially since the vehicle shuts down about every 10 minutes, and that is the classical sign of over-heating electronics that act almost normal until the electrical componet becomes too hot and then begins to malfunction.

The ECM (Engine Control Module) or ECC (Engine Control Computer) for those vehicles were not manufactured very well and were prone to failure, and that is why you can purchase a re-manufactured one for only $85.00-$89.00, and the re-manufactured one will not have the stock defects.

If you do purchase an ECM/ECC and if it has a PROM chip (Programable Removable On-board Memory) that must be installed from your old ECM/ECC be very careful when removing and installing the PROM, and the plastic retainers on either end of the PROM will push back away from the PROM and lift the PROM out of the connector on the circuit board. When installing the PROM be sure that the retainers are pushed back and that when the PROM is pushed down into the connector that the retainers lock in the PROM. Not all vehicles will have a PROM and be very careful with the PROM if you do have one to remove and install because it can easily be damaged, and if it is a necessary procedure to change the PROM, then the ECM/ECC that you purchased should come with a detailed diagram and procedure for you to follow so that the PROM is properly installed into the ECM/ECC.

Here are two links that show the price of the ECM/ECC from a major auto part store depending on if the vehicle has a 2.5 liter 4 cylinder engine, or a 3.3 liter V-6 engine.

Link for 2.5 liter engine.

Link for 3.3 liter engine.

Jun 18, 2010 | 1992 Oldsmobile Cutlass Ciera

1 Answer

Where is the PCM located on a 1991 Oldsmobile 98 Regency elite?

The PCMor powertrain control module is only on 1996 and newer cars.Earlier models have a ECM or electronic control module/pcm.You want to change the ECM if its a 1992.Its located under the right hand side of the instrument panel.The ecm has a prom( programmable read only memory)in it.You will need to remove this from the old ecm and install in the new ecm.The ECM/PCM can be used in many different GM vehicles but the prom is very specific and must be used only in the vehicle it was designed.The prom will not come with the new ecm and must be carefully removed and installed on the new ecm.There also is a CALPAK in the ECM ( A devise for fuel delivery) This may come with the new ECM But make sure all parts are the same.You should get a vehicle repair manual to do this job correctly,and make sure you do not damage your PROM.Your PROM is very IMPORTANT!

Oct 21, 2008 | 1991 Oldsmobile Ninety Eight

1 Answer

84 vette aready changed ECM coil plugs wires map sensor fuel pump and filter and cleaned out gastank but cant get to run i think it is limp home mode but dont know how to fix

This may sound odd, but did you rermember to keep your "PROM" from your original ECM? It is the memory for all the ECM codes and configuration. The new ECM normally doesn't come with a PROM.

Oct 12, 2008 | 1985 Chevrolet Corvette

1 Answer

I have a 1986 chevy Celebrity and they said the prom is going bad wher can I get it part # 2732 af / 05598 please let me know what i can do Thank You Darrell Pine

Usually it's not the prom. The ECM is more believable. When you replace the ECM, you have to install the original prom into the replacement computer.

Jul 27, 2008 | Chevrolet Celebrity Cars & Trucks

2 Answers

Code 53 ecm over 17.7 volts

Have you taken an actual voltage measurement at the battery?
If the voltage is in fact over 15 volts, it can cause all sorts of problems. If that is the case, the alternator will need to be replaced.

May 20, 2008 | 1991 Oldsmobile Cutlass Ciera

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