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Went outside the other day and my F-Type will not start. I tried to hit the ignition button and the console and dash lights all lit up.... As well as all of the fault lights. I walked away because I didn't have time to deal with it. Came back to the car a few days later and it will not start. No console or dash lights. Got out and checked the battery, it was showing Dead. I put a charger on it and waited for a full charge. Tried to start the car and got nothing. Moved a jump box to the front terminals. Car will light up but will not turn over. If I leave it connected it kills my jump box. So, here is my concern.... Why do I have power inside the car when I hook up to the front terminals, but the car does not have power when connected to the battery? In the recent past I have cleaned the ground terminal at the starter, replaced the starter, changed the ignition button, checked the 400 amp fuses, tightened all of the bolts I could find, and purchased a new battery.
I can not get any codes off of the car because it will not power up inside. I am beginning to wonder if the power drain is my alternator and it has gone bad?
The issue will not be your alternator. Your story shouts a faulty battery, meaning that the charge is insufficient…you state that the battery was recently replaced. Was it fully charged before installation? New batteries are rarely fully charged even when a battery tester shows “GOOD”, and in many cases, the use pattern of the car never brings the battery to full charge.
In addition, you may have a battery drain; does the triangular red light on the console remain illuminated more than 15 minutes after shut down?
The problem may be more complex (or simpler) and others will have further suggestions. It might be worthwhile verifying all connections again.
The issue will not be your alternator. Your story shouts a faulty battery, meaning that the charge is insufficient…you state that the battery was recently replaced. Was it fully charged before installation? New batteries are rarely fully charged even when a battery tester shows “GOOD”, and in many cases, the use pattern of the car never brings the battery to full charge.
In addition, you may have a battery drain; does the triangular red light on the console remain illuminated more than 15 minutes after shut down?
The problem may be more complex (or simpler) and others will have further suggestions. It might be worthwhile verifying all connections again.
As sov said, start with a new battery especially if yours is older than 5 years. Also check your grounds, there are several under the car. I had the exact same issue, the ground attached to the bell housing was loose and corroded. Cleaned it up and re-attached, car started right up.
If you’re troubleshooting this on your own, I don’t think there’s any way to avoid getting a proper AGM compatible charger and charging the battery. A “jump box” I take to be a lithium battery for jump starting, which is insufficient for battery charging. So I suggest you start there, with an AC converter charger with AGM mode, and plan to give a typical 4A charger overnight to get the battery up to spec.
If it gets there, then you start looking at why its draining.
If it doesn’t take a charge, then you move to replace battery.
First, the AGM battery charger.
Last edited by chaadster; Apr 15, 2026 at 08:16 AM.
Battery: Has been charged and shows a full charge. Have verified this with multiple scanners just to verify.
Jump Box: Has been used many times to jump start the car and has a fresh charge. The Car will start from the front terminals with the jump box, but will not start with a full battery. If I leave the jump box attached, the car will drain the battery of the jump box, but the Car battery keeps a full charge.
THE CAR WILL NOT START when utilizing the Main battery, not even on a boost charger. There is a disconnect between the two locations some how and somewhere.
Does anyone have a wild thought of what or where the problem can be? I have checked the fuses, not the relays because I have not been able to determine which is which, and have replaced the starter.
Possible one of the main fuses between the battery and engine side is popped, or the connections where the cables hook up between the rear and that front jump point. Let me see if I can find a clearer picture for you.
With no jumpers attached or anything, what is your measured voltages at that jump start point underhood? Also at the battery in the back. The car currently gives ignition on, but does not crank without the jump box, but starts with the jump box attached to the engine bay points, correct?
Battery: Has been charged and shows a full charge. Have verified this with multiple scanners just to verify.
Jump Box: Has been used many times to jump start the car and has a fresh charge. The Car will start from the front terminals with the jump box, but will not start with a full battery. If I leave the jump box attached, the car will drain the battery of the jump box, but the Car battery keeps a full charge.
THE CAR WILL NOT START when utilizing the Main battery, not even on a boost charger. There is a disconnect between the two locations some how and somewhere.
Does anyone have a wild thought of what or where the problem can be? I have checked the fuses, not the relays because I have not been able to determine which is which, and have replaced the starter.
Need to check along this side of the circuit, see where you're losing power. You say the 400A fuse is good, then I suspect the issue would be at the bus bar connections under the right front fender area.
Battery: Has been charged and shows a full charge. Have verified this with multiple scanners just to verify.
Jump Box: Has been used many times to jump start the car and has a fresh charge. The Car will start from the front terminals with the jump box, but will not start with a full battery. If I leave the jump box attached, the car will drain the battery of the jump box, but the Car battery keeps a full charge.
THE CAR WILL NOT START when utilizing the Main battery, not even on a boost charger. There is a disconnect between the two locations some how and somewhere.
Does anyone have a wild thought of what or where the problem can be? I have checked the fuses, not the relays because I have not been able to determine which is which, and have replaced the starter.
This really looks and sounds like a low state-of-charge (SOC) situation. While you still haven't clarified what this "jump box" is, if it's just a battery like I think it is, it's extremely unlikely to be delivering the kind of current you need to achieve appropriate health of your AGM battery. You need a proper charger to even begin this diagnosis.
Additionally, that you say you're using "scanners" to check battery level, while you haven't clarified what those scanners are, typically the term refers to OBD2 port connected devices which, unless they're running a particular (and apparently uncommon for consumer devices) protocol, cause a known "no sleep" problem on the CAN bus that leads to battery drain. Improper use of OBD2 devices may very well be the root problem causing your issues.
Furthermore, while there are a wide range of OBD2 port scanners and capabilities, it's very unlikely that a consumer device is accurately assessing, and is almost certainly not load testing, battery SOC.
I strongly encourage you to start with the easy stuff and to diagnose methodically. I suggest:
1. remove device from OBD2, leave it out, disconnect the battery ground strap for a minute to allow CAN bus to enter sleep mode and stop energizing modules (drawing power) then reconnect strap.
2. get a proper AC powered battery charger/maintainer with a voltage readout and AGM charging modes. If you can get one that works at 15-20A that's great and will deliver additional capacity that might be helpful in other matters, but a 4A charger will do the trick. I'm not an electrical expert, so maybe there's some nuance or additional specs that an expert can elucidate, I'm just speaking from own experience and limited knowledge, not speaking authoritatively.
2. use that charger to fully charge the battery; a 4A charger left on overnight should do the trick and will indicate when charging is complete. Remember to use AGM charging mode. You can do this from the jump point and ground post underhood.
3. After charging is complete, disconnect the charger and see if car starts.
If it works, you're probably golden and just need to remember to pull the battery ground strap after using and removing an OBD2 port scanner. Using your charger in Maintain or Storage mode periodically to ensure optimal SOC should allow your battery to last for years.
@BigJay13 You posted about some previous starting issues, any chance this could be related to the corroded starter wire? If that wire was corroded, this ground wire likely is as well (thanks to @RoverJoe for the pic):
1. remove device from OBD2, leave it out, disconnect the battery ground strap for a minute to allow CAN bus to enter sleep mode and stop energizing modules (drawing power) then reconnect strap. - I do not have access or the ability to hook up a scanner to the OBD2 port on the inside of the car because I DO NOT HAVE POWER INSIDE THE CAR. I am using a multimeter to check the battery, fuses, and continuity across the fuses/ground wires. I do not have power in the car from the Main battery. I only have power in the car when I hook up to the front terminals. This indicates that there is something stopping power from the battery to the starter/front of the car.
2. get a proper AC powered battery charger/maintainer with a voltage readout and AGM charging modes. If you can get one that works at 15-20A that's great and will deliver additional capacity that might be helpful in other matters, but a 4A charger will do the trick. I'm not an electrical expert, so maybe there's some nuance or additional specs that an expert can elucidate, I'm just speaking from own experience and limited knowledge, not speaking authoritatively. - I am using an AC Powered Battery Charger that has a voltage readout and AGM charging modes. I have used that to Charge the Battery and to confirm that it is charged. And just to verify that it is reading correctly I used a multimeter to confirm the read out. It has a boost motor for starting the car, but I am not willing to use it due to a guy friying my Mini Footwell Module by boosting my battery to jump start it. Not willing to take that chance with the JAG.
2. use that charger to fully charge the battery; a 4A charger left on overnight should do the trick and will indicate when charging is complete. Remember to use AGM charging mode. You can do this from the jump point and ground post underhood.
3. After charging is complete, disconnect the charger and see if car starts. -The Car will not start after the full charge. I have to attach to the front terminal with either a charger or another car to get it started. However, when you remove the connection from the front terminal, the car will not start from the main battery.
If it works, you're probably golden and just need to remember to pull the battery ground strap after using and removing an OBD2 port scanner. Using your charger in Maintain or Storage mode periodically to ensure optimal SOC should allow your battery to last for years.
Possible one of the main fuses between the battery and engine side is popped, or the connections where the cables hook up between the rear and that front jump point. Let me see if I can find a clearer picture for you.
With no jumpers attached or anything, what is your measured voltages at that jump start point underhood? Also at the battery in the back. The car currently gives ignition on, but does not crank without the jump box, but starts with the jump box attached to the engine bay points, correct?
RoverJoe, I totally missed your question. The answer is NO. The ignition and ALL lights are off inside the car when powered by the main battery. However, the second I attach a jump box to the engine bay points the interior lights up and I can attempt to start the car. If I leave it attached, something will drain the power from my box and kill it?
Ok then you need to check your main battery grounds and connections. Is there voltage at the jump start points under the hood when you just have the main battery connected and nothing else? I would assume no. Start with the battery grounds in the back of the car. Voltage drop tests across them are the quickest way to test.
Also you could run an external ground wire clamped to the front engine bay ground then to the rear trunk ground to see if you can start from the battery to confirm.