2007 Jeep Compass Electrical

DEWY2

MEMBER
2007 JEEP COMPASS
243,000 MILES

Replaced the battery terminals on the factory lead wires to the battery, (bolted connection to the connectors). Replaced with new ones from auto supplier (top post mount type) as original ones were corroded and one had split open. Accidentally touched the body frame with ratchet handle when tightening the positive side bolt to the cable connector, slight arch from contact with body, no burn marks on frame or ratchet.

Installed the cable successfully, started the engine and had no problems. Left the car over night in garage, then next day worked on car for about an hour and used the dome light to finished off some interior polishing up of the dash board with Armorall. Used light for about 45 minutes off and on, not continuously only for areas garage lighting couldn't give proper light.

Went to start the car when finished and the car would not start, lights came on and relays "clicked on", and starter clicked once, then all dead. Rechecked all connections at the battery and everything looked good, got out my new battery charger and put it on the battery terminals overnight and checked in morning. At first the charger read 7 or 8 amps when initially installed, when read 18 hours later the battery was fully charged and green light on the charger was lit indicating the battery was fully charged and the amps read 0.

Started the car right up with no problem, shut it off and restarted with no problems. Left the car overnight in the garage. Started the car the next afternoon, drove it to the store which is about 10 minutes away, without any problems. Parked the car and went into the store, after about 15 minutes went back to car and used the keyless entry system, lights came on, but not interior lights or instrument lights, no chimes, no radio. Put the key into the ignition and turned the key to on position. No power to anything.

Checked all the fuses and relays in the engine compartment, all looked OK, had a store person try to boost my car to see if my battery was low. No go. Touched the tow jumper cable ends together quickly to see if there was any juice in the battery and got a good spark, so battery is powered up. Called AAA and they tried to figure it out, but to no avail. While the AAA technician was sitting in the car the lights came on by themselves without him doing anything, then back out again. He tried moving the battery connections to see they were loose, removed them and reinstalled them, the interior lights came off them off again, but not start.

When the technician did get the light to come on for a very short time period (three times) he tried to turn the key to the on position, but all power went dead. He said it could be a bad ground or a bad relay somewhere but that it would need to be looked at in a repair facility. He towed the vehicle to the garage and I am awaiting a call to see what it might be.

Can you advise on what your best guess would be. Any assistance would be much appreciated. I am not a mechanic and don't want to be "hoodwinked" for expensive fixes that are not necessary.

Kind regards,

dewy2

1 Reply

CARADIODOC

MECHANIC
33,738 POSTS

I could tell you the most common cause of this but it's not the only one. If something more serious is wrong it sounds like you're going to assume your mechanic is lying to you. In my estimation, in the times I've been asked to interpret or clarify the mechanic's side of a conversation, poor communication, unreasonable expectations, or consumers unknowledgeable about how their cars work and the limitations and regulations mechanics work under are the major contributors to assuming the mechanic or shop was dishonest when in reality they were not. As with doctors, accountants, and carpenters, mechanics speak their own language. Most of them can share volumes about your car to another mechanic with a half dozen words, but they do a very poor job of sharing the same information with car owners. If you look at your mechanic as your advocate and not your adversary, you will be less likely to feel ripped off. There's always disreputable people in every profession, but most mechanics want to do what's best for you long term. Be aware too that if a mechanic does something dishonest, he runs the risk of being found out by knowledgeable car owners or a mechanic at another shop, especially if that second mechanic is asked to fix the original problem. If the dishonest mechanic is found out, he will likely lose his job. Shop owners are already fighting the negative stereotype and they aren't going stand for an employee ruining their reputation. Except for some large chain repair shops, almost no independent shops or dealerships pay their mechanics commissions to sell more parts. They may have incentive programs to look for things that are legitimately needed, but so many car owners neglect maintenance and unusual noises and vibrations that there is plenty of needed work to be found already. Also, many shops are so busy, they have to take people by appointment. What good does it do to find more needed work if they don't have time to do it? I WOULD expect any mechanic to point out safety and reliability concerns to be sure the owner is aware of them.

Now, for that "easy" fix, some of your observations don't fit exactly so I'll probably be wrong, but a common cause of intermittent electrical systems is loose or dirty connections on the two smaller battery wires. The positive one is bolted to the under-hood fuse box and is responsible for 99 percent of the problems. The negative one bolts to the body and can cause the same symptoms. The problem here is you need it to act up so it can be diagnosed. When it's intermittent and it's currently working, there is no defect to be found. Those are very frustrating for mechanics and car owners. Too many people poke and tug in an effort to get the system working, then they can't get it to fail when they want it to. That is one of the limitations I referred to the mechanic is working under.

As for that arc when you replaced the cable ends, that's why we always teach to remove the negative cable first and connect it last. That way if your wrench hits the body while it's on the positive terminal, there won't be a spark. That arc almost certainly didn't cause a problem, but it is possible to weld the wrench in place and turn it red hot. I saw that happen once. What scares me more is any spark near the battery including when disconnecting and reconnecting cables can cause an explosion. Batteries give off hydrogen gas. You'll see all battery chargers come with a warning to turn them off when connecting and disconnecting them because they will also cause sparks if they are turned on.