Blowing the 20 amp starter fuse

My car intermittently blows the starter fuse when starting. It started out doing it once every couple of months and would always start with a second fuse. Then it blew 5 fuses in a row and I had to have towed to a shop. The shop said they isolated the problem to the fuel pump and replaced it. It then worked fine for months. Now it is back to blowing intermittently. They think it might be the starter but are not sure. After getting the car to start once with a 25 amp fuse (vs. the called for 20) it started each time for them with the 20 amp back in place so it is hard to be sure.

The questions are 1) Does this seem like it could be the starter or if not what might it be? 2) Any recommended trouble shooting steps (either for me or the shop) to try to pin this down when it is not blowing a fuse. 3) Some have suggested putting in a 25 or 30 amp fuse and driving it like that - the shop does not recommend this - any thoughts?


- 1996 Chrysler Sebring convertible (green, blown top :))

- Temp does not seem to be an issue ? It started acting up in 70 degree weather, then started blowing fuses each time when it was colder ? when they replace the fuel pump. Then started up again when it was close to 0 ? but then worked fine with the temp in the 20s and is now acting up again with the temp in the 30s.

- The shop admits that they don?t get a lot of this type of car, but I am in a small Alaskan town and the nearest Chrysler dealer is 70 miles away.



A look at a schematic shows this fuse (No. 8, 20 amp, hot all the time) provides power for for the starter solenoid through a separate starter relay.
The problem should be one of 3 things.

  1. Intermittent short in the red wire to the relay or in the brown wire to the starter solenoid.
  2. Internal problem in the solenoid.
  3. Faulty starter relay. (This could be caused by burned contact points in the relay. Burned points will provide a bad connection through that circuit. This in turn means that current draw can spike upwards and over time could pop a fuse.)

If one was looking for the easiest and cheapest way out then the relay could be changed to see what happens. Tracking a wiring short is a bit more difficult and if the starter solenoid were replaced then it should be changed in conjunction with the starter motor since a worn starter motor can wear out the solenoid. It will not wear out the previously mentioned relay though. A relay problem could just be due to age and the number of key cycles it has gone through.

Hope that helps. :slight_smile:

If you can find anyone who can read a wiring diagram and use a voltmeter, kidnap them! The 12 volts power supply from that 20 amp fuse is distributed to more circuits than the start circuit. The electrical short / overload could be in any of those branches. When power branches like this, the branches have to be checked and disconnected to find the fault. Good luck in finding an electrician.

It might be worth changing the starter. First,have a look at the ground wire that should connect the engine to the body. If it’s tight and has no corrosion on the connectors, you can just change the negative battery cable because you can almost bet that something is wrong with it. Who needs a test when we’re talking about nickel-dime items. After you check and change cables, you can see how things go before changing the starter.

I’d like to amend this a bit after digging through the schematic some more and discovering something that is somewhat odd.
It shows that they have tied the starter solenoid, which is a comparatively low current item, into the main power lead for the condenser fan, which consumes a high amount of current even when the fan is good. A dragging fan will use much more current and this could be knocking the fuse out.

With the engine off, and cold, see if you can spin the fan blade freely with a fingertip. If the blade is somewhat difficult to turn that could be your problem.
An inductive ammeter could also be used to check the fan current draw when it is running. The important part here could be the current surge when the fan first starts.

A good fan may draw 4 or 5 amps and a worn fan could draw 8-9 amps during normal running. The initial current surge on a worn/dragging fan may hit 15 amps when it first comes on and could be what is knocking the fuse out.
Fifteen amps may not be enough to blow the fuse on a one time deal but this repeated current surge due to the fan cycling on and off can weaken the fuse and eventually pop it due to heat.