1990 Weird battery issue


New Member
Feb 20, 2017
So my mustang has been running wonderfully the past couple months since its last problem. Anyways I'm having some trouble with it now.
When I last turned off the car I left the windshield wipers in the on position, when I went to crank it, the windshield wipers came on for a split second, heard a single click noise instead of the engine turning over, and then everything in the car went dead. I figured the battery was just dead due to me leaving the wipers in the on position.
Anyways jump started the car and it really didn't want to jump start, the car ran really rough at idle for a solid minute and I had to keep my foot on the gas to keep it from stalling.
After a while, the car ran normally and I drove it home.
Now every time I go to start it through the same thing happens. One click and then everything dies, the battery is instantly having all charge sucked out of it, and I have verified this using a charge meter I have on the battery.
I figure the issue is either with the ignition switch, which is cracked like the ones Ford recalled in the 90's, the starter relay, or a broken ground somewhere.
If anyone has dealt with this problem or has any insights I would appreciate it.
Again the issue lies with the battery instantly draining itself upon crank, please don't tell me this impossible or incorrect because I have verified myself that this is indeed what is happening.
Thank you in advance.
Last edited:
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Mod Dude
Jul 7, 2005
Sounds like you lost a cell in the battery from it being drained completely when you left the wipers on. I would get the battery tested at the auto parts store


StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
Dublin GA
No Crank checklist for 5.0 Mustangs

Revised 24-Oct-2013 to update voltage drop figures.

No crank, slow crank and stuck starter solenoid problems have the same root causes – low battery voltage and poor connections. For that reason, they are grouped together.
Use the same initial group of tests to find the root cause of slow crank, no crank and stuck solenoid problems.

Since some of the tests will bypass the safety interlocks, make sure that the car is in neutral and the parking brake is set. Becoming a pancake isn’t part of the repair process…

1.) Will the car start if it is jumped? Then clean battery terminals and check battery for low charge and dead cells. A good battery will measure 12-13 volts at full charge with the ignition switch in the Run position but without the engine running.
A voltmeter placed across the battery terminals should show a minimum of 9.5-10 volts when the ignition switch is turned to the Start position and the starter engages or tries to engage. Less than this will result in a clicking solenoid, or slow cranking (if it cranks at all) or a starter solenoid that sticks and welds the contacts together.

Most auto parts stores will check your battery for free. It does not have to be installed in the car to have it checked; you can carry it with you to the auto parts store.

The battery posts and inside of the battery post terminals should be scraped clean with a knife or battery post cleaner tool. This little trick will fix a surprising number of no start problems.

The clamp on with 2 bolts battery terminal ends are a known problem causer. Any place you see green on a copper wire is corrosion. Corrosion gets in the clamped joint and works its way up the wire under the insulation. Corroded connections do not conduct electricity well. Avoid them like the plague...

If the starter solenoid welds the contacts, then the starter will attempt to run anytime there is power in the battery. The cables and solenoid will get very hot, and may even start smoking. The temporary fix for a welded starter solenoid is to disconnect the battery and smack the back of the solenoid housing a sharp blow with a hammer. This may cause the contacts to unstick and work normally for a while.

A voltmeter is handy if you are familiar with how to use it to find bad connections. Measure the voltage drop across a connection while trying to start the car: more than .25 volts across a connection indicates a problem. The voltage drop tests need to be done while cranking the engine. It's the current flowing through a connection or wire that causes the voltage drop.

See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help for help troubleshooting voltage drops across connections and components. .

Voltage drops should not exceed the following:
200 mV Wire or cable
300 mV Switch or solenoid
100 mV Ground
0.0V Connections
A voltage drop lower that spec is always acceptable.

2.) Check the battery to engine block ground down near the oil filter, and the ground behind the engine to the firewall. All grounds should be clean and shiny. Use some sandpaper to clean them up.

3.) Jump the big terminals on the starter solenoid next to the battery with a screwdriver - watch out for the sparks! If the engine cranks, the starter and power wiring is good. The starter relay is also known as a starter solenoid.

The rest of the tech note only concerns no crank problems. If your problem was a stuck solenoid, go back to step 1.

4.) Then pull the small push on connector (small red/blue wire) off the starter solenoid (Looks like it is stuck on a screw). Then jump between the screw and the terminal that is connected to the battery. If it cranks, the relay is good and your problem is in the rest of the circuit.

5.) Remember to check the ignition switch, neutral safety switch on auto trans and the clutch safety switch on manual trans cars. If they are good, then you have wiring problems.

Typical start circuit...
Diagram courtesy of Tmoss & Stang&2birds

6.) Pull the starter and take it to AutoZone or Pep Boys and have them test it. Starter fails test, then replace it. If you got this far, the starter is probably bad.

Starter solenoid wiring for 86-91 Mustang

Starter solenoid wiring 92-93 Mustang or earlier Mustang with upgraded high torque mini starter.

Electrical checks for the switches and starter solenoid
Remove the small red/blue wire from the starter solenoid. Use a screwdriver to bridge the connection from the battery positive connection on the starter solenoid to the small screw where the red/blue wire was connected. The starter should crank the engine. If it does not, the starter solenoid is defective or the battery lacks sufficient charge to crank the engine.

If the starter does crank the engine, the problem is in the clutch safety circuit (5 speed) or Neutral Sense Switch (auto trans) or ignition switch.

See the Typical start circuit diagram above for wiring information for troubleshooting.

You will need a voltmeter or test lamp for the rest of the checks. Connect one lead of the voltmeter or test lamp to ground. The other lead will connect to the item under test.
Look for 12 volts on the white/pink wire when the ignition switch is turned to the Start position. Check the ignition switch first.
No 12 volts, replace the ignition switch.

The next step will require you to push the clutch pedal to the floor (5 speed) or put the transmission in neutral (auto trans) while the ignition switch is turned to the Start position.
Good 12 volts, check the clutch safety switch (5 speed) or Neutral Sense Switch (auto trans) for good 12 volts on both sides of the switches. No 12 volts on both sides of the switch and the switches are defective or out of adjustment. Check the wiring for bad connections while you are at it.

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
polk county florida
You either have a battery problem like mentioned above or you are losing connectivity at a connection, check battery cables at the solenoid and block ground.
Now that cracked ignition switch needs to be replaced.
Crap, I see jrichker already posted his expert advice :doh: I'm just too slow.


New Member
Feb 20, 2017
Problem has been solved! Thanks to those who helped. Problem was a combination of a bad ignition switch and also corrosion on the neutral battery leads.


New Member
Feb 20, 2017
I take that back problem is not solved. Cleaned the battery leads and the car started on the first crank. Now I went to start it a second time and the same problem as before occurred. When I check the neutral leads they are covered in corrosion again and the battery is drained. What's causing this?


StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
Dublin GA
Before you spend $$$, charge the battery overnight and then take it to the local Auto parts store to have it tested.

If you can jump the battery and get the engine to run reliably, have someone follow you to the auto parts store and have them test the charging system and the battery. Just don't turn the engine off until thy have finished doing the testing. All the major automotive chain stores can do this for you.


You have a nice rear end there Dave.
15 Year Member
Nov 29, 1999
Mililani, Hawaii
I agree it sounds like your battery. Leaving the wipers on with the ignition off should not have had caused anything. If the ignition was off the wipers don't have power.
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