Pin #10 at the cluster connects to the Programmable Communications Interface (PCI), which allows the PCM to share the coolant temperature, oil pressure, charging voltage, tachometer, speedometer, and fuel level data with the instrument cluster. So, I was surprised to find the battery at 11v following a sub-freezing blizzard sitting just 1 day. When I added a normal 20 mA parasitic drain to 180 mA battery drain at the 50-amp maxi-fuse, it equaled the 200 mA indicated at the body-to-battery negative ground wire. Opening a hood or door on a modern vehicle can “wake up” multiple modules in the networking system. Overnight it is ok. (Bought a new battery -- still draining.) I have an appointment to take it to the dealer AGAIN for this reoccurring problem and I was just curious if it was a common problem. I met an engineer working for a major tire manufactures in US. When your car battery dies once, it may be tempting to just write it off as a fluke. 3. 4. So if it seems like the battery is dying with the engine running, there’s probably an issue with your charging system.
I advised the shop to save diagnostic time by testing and fully recharging the battery. Photo 4: As discussed, locating the source of a parasitic drain can be very time-consuming. You will then need to identify the corresponding circuit, which will help you track down the specific component that is causing a problem. If it seems like your battery keeps dying while you’re actually driving your car, the root problem probably isn't the battery. And honestly, the battery could have an issue even though it's only 2 months old. In this situation, the harness must be removed, opened, and repaired, which is a labor-intensive job that might exceed the vehicle’s market value. Corroded battery connections can prevent the charging system from topping off your battery when you are driving. While I readily acknowledged that possibility, I wanted to confirm that by checking the mechanical instrument cluster wiring schematic. Not a problem because I knew that my original parasitic drain remained at 240-250 mA. By keeping on top of corrosion, making sure that the battery connections are tight and secure, and not allowing the electrolyte in a non-sealed battery to drop, you can actually help your battery last much longer. I got it to finally turn off after hitting the on off button like 8 times. When discussing body control electronics, it’s important to understand that before 2004 when Controller Authority Network (CAN) technology was introduced to the domestic market, most domestic vehicles were using a very simple body control topology (configuration) consisting of a high and low-speed data transmission system. In most cases where an alternator isn’t charging and the engine actually dies, it’s simply a case of a bad alternator that needs to be rebuilt or replaced. You can locate many abnormal parasitic loads using a simple method. The easiest way to go about this type of diagnostic is to leave your multimeter or test light connected and remove individual fuses until the drain disappears. Photo 1: An improperly installed aftermarket sound system nearly ruined the electrical system this 2000 Jeep Grand Cherokee. Stay up to date with the latest Underhood Service news.
You may also have a belt that uses an automatic tensioner, in which case that can also be the problem. My client shop believed that the PCM was defective. If any corrosion is present between your battery terminals and cable connectors, it will interfere with the ability of the starter motor to draw current from the battery and the ability of the charging system to top the battery off. 2004 Jeep Liberty... new user needs help... Jeepz.com has one of the friendliest Jeep forums on the internet. Some of these problems are enough to kill a battery on their own, while others are usually coupled with a battery that is already weak or on its last legs. My client shop quickly recognized that the high-amp sound system installed in the Jeep was likely causing the high-amperage battery drain and, with the current owner’s permission, removed the system. But keep in mind that the testing should be done outside to expose the modules to changes in ambient temperature and humidity. If your car battery keeps draining, the first things to check are your lights. Not sure if the car turns off after a bit and not willing to try. A wiring schematic indicates that “Gen Source” (PCM pin #25, connector #3) and “GEN Field Driver” (PCM #10 connector #2) lead to the brush assembly at the alternator. This allows all modules to time out and remain “asleep.” So let’s solve this month’s Diagnostic Dilemma by working through a more advanced level of parasitic battery drain diagnosis on two case-study vehicles, a 2000 Jeep Grand Cherokee with a battery drain and a similar 1998 Grand Cherokee with a module drain.
Some shops and parts stores will load test your battery for free if you don’t own a load tester, while others will charge a nominal fee. Had a Chevy Cobalt that I couldn't get started half the winter the first year of ownership due to poor CCA rating. While measuring the voltage drop across each of the interior “junction block” mini-fuses, I located a voltage drop across mini-fuse #23. I hope your problem is easily solved. The Jeep was then sold to a second party, who didn’t realize the complexities involved with solving this battery drain problem.
He is also a systems administrator for an IT firm in Texas serving small businesses. With the engine running, the instrument cluster quit displaying data. My client shop had previously pulled code P1687 (no cluster bus message). Auto Care Association To Hold Unified Event, BOLT ON Hits 50 Million Repair Photo Milestone, Service Pros Can Schedule Certification Tests Online, J.D. If your alternator belt is loose, you may be able to tighten it. Hot or cold weather won't kill a battery that's new or in good shape, but a weak or old battery may fail in extreme conditions. The Trouble With Checking a Charging System at Home, How to Keep Your Battery From Repeatedly Dying. Cars15, none of the accessories like the heater fan, wipers, or radio will drain your battery when the Wrangler is off, nothing should stay running. After I charged the battery it cranked over, started right up, and has not been a problem since. If you’re dealing with a situation where your battery goes dead over and over, there’s a good chance that every time it dies like that, the ultimate lifespan of the battery is shortened. Loose or stretched belts and worn tensioners can prevent an alternator from working. I'll post my story just in case that doesn't solve the problem. When everything is working correctly, you can walk away from a vehicle like this, and everything will shut off on a timer.
Since an active relay is warm to the touch, my first step was to check each relay for warmth. Keeping in mind that most manufacturers now publish parasitic drain values, let’s assume that a battery drain exceeding 50 mA is cause for concern. 2. Wow funny thing is my radio is now staying on after my dealer told me they "updated it". Electronic: VIDEO: How Modules Manage Alternator Power, Electronic: VIDEO: Checking Key Fob Signal And Operation, Diagnostics: VIDEO: No-Start No-Crank On Vehicles With Transponder Keys, News: Auto Care Association To Hold Unified Event, News: BOLT ON Hits 50 Million Repair Photo Milestone, News: Service Pros Can Schedule Certification Tests Online, News: J.D. 2018 Compass Latitude w/Romik Runningboards. Doing otherwise runs the risk of blowing an expensive fuse inside your meter. My client shop quickly recognized that the high-amp sound system installed in the Jeep was likely causing the high-amperage battery drain and, with the current owner’s permission, removed the system. Common drains include glove box and trunk lights that come on, or remain on, when they shouldn't. If you come back half an hour or an hour later, and things like the headlights are still on, that's probably why your battery is dying. The compass has two of them? Waiting on a replacement! 8 Posts . Some headlights are designed to remain on for a while, but a malfunctioning system may leave them on permanently. The Jeep was then sold to a second party, who didn’t realize the complexities involved with solving this battery drain problem. Diagnosing any modern networked system with multiple modules requires an accurate low-amperage current probe and adequate service information. But these were no-code pattern failures and easily solved by replacing the body control module. Apparent logic leads to a diagnostic scenario in which the alternator field circuit amperage increased to far more than needed for normal electrical loads (shorted rotor?). I mean dead to the point the doors won't even unlock. Once the engine is running, the charging system takes over. Removing fuse #7 eliminated the 180 mA drain. It laughs at the cold - seems to actually start better and crank faster in cold than hot. Going a step further, disconnecting the BCM eliminated the battery drain. And just check your connections on the battery. Apparently after a batch of tires are manufactured, batches are graded based on the quality of the rubber etc. The answer is “yes” because many years ago, I experienced problems with the old ‘90s-era Chrysler body control modules (BCMs) “waking up” at night, presumably in response to changes in ambient temperature and humidity. Cold weather is when bad batteries show up. I noticed it the other day after I came outside to get something from my car. What Causes a Car's Electrical System to Suddenly Stop Working?
I recently learned this is also true for the factory installed tires. In one memorable case, the BCM would activate the HVAC blower motor and drain the battery. Our first case study is a 2000 Grand Cherokee (Photo 1), that was draining the battery so quickly that the original do-it yourself owner had installed a master switch to disconnect the battery (Photo 2). Parasitic drains can be difficult to find, but they are fully capable of killing batteries dead. After verifying ignition switch operation, I’m ready to recommend replacing the BCM. You can also test your battery with an inexpensive tool called a hydrometer, which allows you to check the specific gravity of the electrolyte in each cell. Photo 2: The owner of this Grand Cherokee installed a master switch on battery negative to prevent the battery from discharging overnight. The problem with using a test light is that it can be very difficult to tell how much of a drain is present just from the brightness of the light.