Question about 1999 Pontiac Grand Prix

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How can you tell if the ECM is bad?

My check engine light will not appear on dash when I go to start the car.

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  • yadayada
    yadayada May 11, 2010

    there is no test for this, u go by skill aand knowledge of the system. The PCM is the last thing that fails 99% of the time, replaced maybe 20 in 30 years and 1000's of repair jobs.



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  • 152 Answers

If the light does not come on when you turn the switch on but not start, more than likely the bulb is burnt out. It should come on in bulb test mode. Unfortunately you need that light to diagnose the ECM.

Posted on Apr 15, 2009


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2 Answers

How can you tell when the ecm is failing

Lot of time car cut out you speedometer cut out or dont start key on no check engine on the dash

Mar 11, 2015 | Cars & Trucks

1 Answer

Can a vehicle run with a non functioning ECM?

if the check engine lite doesn't work it most likely needs cluster removed and bulb replaced its blown. if the computer is bad it wont run. I wanna say that ecu fuse will clear code from computer but its not main power to it. I would start with the bulb that way you can get code.

Feb 18, 2015 | 1994 Toyota 4Runner

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Engine light on

This dashboard light on modern cars sometimes fills people with dread. In reality it is your friend as a car owner, and one of the best advances ever to appear on cars. The ECM computer which runs your engine has many sensors connected to it which tell the ECM about conditions in your car systems. For instance, it monitors the air temperature in your air filter, helping it to run your engine in the most efficient way.

When this light comes on it is telling you that the ECM has stored a diagnostic trouble code, or DTC, based on signals it is receiving. You could then go to a mechanic or auto electrician to have this code read out. In some countries (e.g. the USA) you can have this done for free at an auto parts store, or buy your own tool to read the code, called an OBD II scanner, for about $50.

However it goes, if you know the code, you will be much better able to judge what the mechanic tells you about the repairs needed, and the likely costs, The codes themselves are not very informative, and you will probably need to Google it or look up a maintenance manual. A code may appear as, for instance, P0131.

There are some codes which appear more frequently, and deserve special mention:

- Faulty oxygen sensor. There may be 2 or 3 of these in a car, and they do wear out.

- Faulty emissions system. The first thing to check is the fuel cap. It may be loose or require replacement.

- Faulty knock sensor. This enables the ECM to adapt to different grades of fuel.

- Faulty catalytic converter. This is part of the exhaust, next to the muffler.

- Fuel mixture too lean. This will usually be caused by an air leak in the intake, perhaps a loose air cleaner cover or cracked hose.

- Engine misfire. Often caused by old spark plugs or cracked plug leads.

Jan 09, 2013 | 2006 Volvo S40

1 Answer

Enginesign on dash;light shows ,what does it mean ?

First of all you need to access the Engine Control Module (ECM) using suitable diagnostic equipment connected to the data link connector of the car, in order to pull out all DTC's memored. DTC = Diagnostic Trouble Code. Then you will bu full informed about the root cause of the problem, and you will be able to repair & replace bad pieces and reset the ECM. Then the engine check & EPC (Electronic Pedal Control) yellow lights will turn OFF.

The check engine light:

The check engine light & EPC light:

Sep 23, 2011 | Cars & Trucks

1 Answer

I have Grand Cherokee 1995 6 cylinder,I am facing starting problem now, in morning and if my jeep is in parking 4 to 5 hours,and I need to start the ignation my jeep does't start its take time 20 to 30...

Your ECU is going bad and needs to either be replaced or repaired. That 'no check engine light for 20-30 minutes' is a common problem that tells it's an ECU problem.The ECU won't power the fuel pump and other relays until the check engine light illuminates on the dash.

Jan 15, 2011 | 1995 Jeep Grand Cherokee

1 Answer

Fuel pump not running no fire when trying to start

If you have no fuel pressure and no spark when cranking, that sounds like your ecm is bad. If the Check Engine Light is not illuminated on the dash, when you turn on the ignition, then the ecm is definitely bad. Have it checked out.

Nov 03, 2010 | 1993 Jeep Cherokee Country

1 Answer

1996 Jeep 4.0 GC, will not start. Engine will crank, will not fire, no dash check lights.

Sounds like your ECM is bad, if you have no check engine light on your dash when trying to start. Have it checked.

Nov 02, 2010 | 1996 Jeep Grand Cherokee

1 Answer

Was driving now no spark for ignition do you think its ignitor or a coil?

It might be your ecm going bad. When the jeep dies, does the check engine light illuminate on the dash or is it gone till the jeep is able to restart? If it does not light up when the jeep dies, then the ecm is definitely going bad and will need to be replaced. If there is no problem with the check engine light, then proceed with checking the coil.

Sep 29, 2010 | 1997 Jeep Grand Cherokee

1 Answer

2002 chrysler 300 M 3.5 liter immediatly quits after starting.

The ECM is most likey the culprit but I would check ground wires and wiring harness to be sure they aren't faulty. With you telling me the voltage is too high, it pretty much points to wiring but the ECM may have gone bad and its just sending blind signals hence the high voltage. The engine light isn't coming maybe because of the ECM isn't working. Pray it isnt the ECM, its costly but exhaust your options by checking wiring and ground beforing fingering the ECM

Dec 06, 2008 | 2001 Chrysler 300M

1 Answer

2002 malibu ECM

not bad ecm it has to be programed by a dealership to mach your cars electronics radio,lights,sensors,ect,ect,ect

Sep 29, 2008 | 2002 Chevrolet Malibu

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