Had trouble starting car, negative battery terminal was cracked, replaced that, now it still wont start, it makes a click as i turn on ignition, sometimes it starts straight away other times take a while.

Hi, i would get the starter motor checked 1st.

check tightness,clean battery terminals,or inline fusable link next to the positive cable,

replace ignition switch.

First make sure you have good battery connections. A poor connection will give enough power to turn on head lights but not turn on starter motor. Clean the connections and ensure they are tightened.

If connections are good, check voltage of battery. It should be at least 12 volts.

If battery voltage is low, either charge the battery, or attempt to jump start the car (red to positive terminals, black to negative terminals; attached positive first, prefer to attach negative terminal to a good metal location other than the negative terminal on the battery).

If the starter motor is visible, try tapping lightly with a mallet to free it up. This may or may not work depending on the problem. If the car starts, replace the starter motor anyway or it will strand you again.

Most cars have a starter relay and a fuse for the ignition. Do a Google search on the internet for your model of car, or look in your owners manual to find the location of the solenoid and/or fuse. Replace the fuse if it's burned out. Note that a shorted starter motor could cause the fuse to burn out, so replacing the fuse may not fix the problem. Suspect a shorted starter motor or wire if the fuse burns out again. You may need some professional assistance at this point to check the solenoid.

If the solenoid is bad, it is usually replaced along with the starter. Remove starter motor/solenoid and take to an Autozone or Oreilly or equivalent and have them check its functionality. Be sure to disconnect the battery's negative terminal before removing the starter motor.

If the starter is good, then your problem is likely either your car's security system (check if security light is flashing if you have such) or check the ignition switch. If you have a mechanic friend, see if he can bypass the ignition switch and get the starter motor to turn over.

Poor electrical connections or a bad battery or a bad starter motor/solenoid are the most likely culprits.

check all connections for tightness, sounds like one is loose somewhere between the battery and the starter or a ground is not tight..turn lights on and see if they go dead when key start is turned,,check the engine to frame ground also(usually a flat braided wire)..if lights go dead when key is turned need to charge the battery for around 4 hrs with a 6 amp charger and try again..may also be a neutral safety switch,,if not out of gear it wont start,,

bad connection from the terminal youll need a battery jumper cable. But first lets try this make sure battery terminal is tight and clean okay next now we are going to find the weak link. Take the negative battery cable and the jumper on negative cable on battery and put the other end of that cable to body ground there we made a better cable ground connection. ck to see if problem solve, If yes correct negative terminal. If no problem in positvie section you need to make sure positive is clean contact.

p1684 just means the battery has been disconnected. Check the tightness of the battery terminals. make sure the terminals are free of corrosion..

When you say " wont start", are you saying the engine wont turn when turning the ignition key or the engine will turn over but not run?

check to make sure the small black wire that runs to the negative battery terminal is connected properly and corrosion free it will cause this issue / hope this helped

I would be more suspicious of the fuel system. Have you changed the filters lately? Do you have a 6.2 or a 6.5?

A seriously shorted alternator can do this too.
Try this:
- Disconnect the negative terminal of the battery - Replace the fried wire - Remove the lead that runs from either the positive battery terminal or from the starter terminal to the alternator; the idea is to get the alternator out of the circuit temporarily. - Reattach the positive battery terminal (if it had been removed) - Reattach the negative terminal - Try starting the engine
If the engine will now start and the wire you replaced doesn't fry again, the alternator is badly shorted and will have to be replaced.