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92 Deville resistor in PCM burned. Does anyone know what this resistor does? See Pic

1K views 10 replies 6 participants last post by  rmbb 
#1 ·
Does anyone know what this resistor in the PCM does?* Motherboard Computer hardware Electronic engineering Electronics Electronic component


This is in a 1992 Cadillac Deville with the 4.9 V8.
 
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#4 ·
It is tough to say exactly what it is withought seeing it in person but. It looks like a Metal Oxide Varister. This component is responsible for keeping high voltage transients from damaging the PCM. Chances are that the computer you are using has a power strip with a circuit breaker on the side. This strip uses a Metal Oxide Varistor to protect your computer. They work by shorting out whenever the voltage goes over a pre determined level. This is supposed to blow the fuse and protect the electronic device. It looks like you have more trouble then just a blown Varistor. It looks like you may have a burned PC Board tracing. This kind of damage can happen when a fuse of too high a rating is used instead of the correct one. You could check the rest of the board by just removing the MOV and trying to power it up. I can almost assure you that you are in need of a new Computer as mentioned above.
 
#5 ·
Hey that's interesting. This is the PCM that is in my car now since a year back. I bought a used one and felt that the car wasn't running any better with the used one so I stuck to my old one.

aeronca36606-> So, what happend here do you think? I have lots of other components that were fried in the car when I bought it. I got it cheap but the instrument cluster was dead (I had to buy a new one and install). Also the SRS box was dead, it looked even worse and used to smell when I ran the car. I have just taken the box out now.*
 
#7 ·
I would suspect either the battery was hooked up backwards or the car was improperly jumped with a dead battery. It also may have had the battery disconnected while the engine was running. The battery not only stores energy to start your car but it also soaks up voltage transient in the electrical system. It acts like a huge capacitor. A car alternator is capable of putting out over 100 Volts if left to run away. The battery helps to keep this from happening. When jump starting a car with a completly dead battery do not disconnect the cables until the battery has a chance to get a minimal charge.
 
#8 ·
. When jump starting a car with a completly dead battery do not disconnect the cables until the battery has a chance to get a minimal charge.

..................... because
- to the vehicle's voltage regulator - a dead battery "looks like" a 100% short to ground.
 
#9 ·
I was thinking more of a battery that was so flat, from a car that was in storage for a year or two, that it had no ability to absorb any charge current. To the vehicle's voltage regulator this would look like there was no battery in the system at all. As you explained a dead battery from leaving the lights on over night will look like a short to the Regulator. This is also is very hard on the alternator as it puts it in a maximum charge condition and if it is older or weak can toast the alternator very quickly. (for instance blow a rectifier diode). I will bet that you have had this happen to you. I know it has happened to me several times! By the way are you near the airport? I used to fly in there from time to time in years past. Great seafood around the corner.
 
#10 ·
I live 2 miles NNE of Bay Bridge Airport. Still plenty of good restaurants locally. South Kent Island - Kentmorr Airpark, grass strip. Used to fly a J3 and a TriPacer in and out of there in the 60s. Kept both planes at the old Waterford (CT) airport in New London. Diversions while on sub duty. Flew down to College Park Airport for visits to home.

My 1945 J3, N42592, is still listed in the FAA aircraft locator, somewhere in Oklahoma. Out of certificate. I'll bet it's a basket case.

Yep - a battery, dead for 2 years, would be so badly sulfated that it would never charge/recover. Once that lead sulfate on the plates turns crystalline it's the end for the battery.
 
#11 ·
Very interesting. It does sound plausible that this is what happend. When I bought the car the old man told me the battery was brand new, which it is. They've made a conversion to Euro style battery poles. It is not difficult exactly to find a battery with the American type poles with screws on them but it's much easier to find the eurostyle that just hooks on.

If you were talking to me asking about the Airport than yeah Im not too far away from Kastrup Airport in Copenhagen :)
 
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