REPAIRING A WIPER SWITCH

How to fix a wiper switch with the symptoms that the windshield wiper (or rear wiper) works only in LO speed and not in the intermittent and HI positions. 

The wiper switch assembly controls the main windshield wipers as well as the rear window wiper (if equipped), misters/washer fluid, and hazard lights. On 88-89 Convertibles, the wiper switch controls convertible top operation instead of rear wiper, and on 90-91 Convertibles, the cruise control on/off is part of the switch instead of rear wiper or top control. 

New wiper switch units are available from Mazda dealers and Mazdatrix for typically around $300-$400 (price depending on model). The problem is typically bad contacts in the relays. This is caused by Mazda’s supplier using unsealed (allowing humidity and moisture to build up) and low current capable relays. So the problem of switch failure is often just put off for a couple of years, if the entire switch is replaced with a new part.  Some people will pop open and clean the contacts, but again this only temporally fixes the issue, and is not a long term fix. 

Replacing the relay entirely with a new sealed high current version however will solve the long term enviable failure.  Omron, the company that supplied the  relays to Mazda’s switch builder, has a replacement relay that meets our needs for both high current capability and sealed against the elements; the G6C-2114-US-DC12.  There is also a heavy duty version of the relay with gold contacts and no lead available from Panasonic.  Both relays are available only through distributors, such as Digikey.

REMOVING THE WIPER SWITCH

If you are unfamiliar with working on cars and automotive electrical system, it is recommended that you first disconnect the NEGATIVE battery cable to prevent accidentally shorts or electrical damage.

On all coupes and 88-89 convertibles without tilt steering, first remove the steering column surround.  There are 4 screws accessible from the bottom of the surround.  There is also a trim ring around the key hole that will need to be popped off for the lower surround section to be removed.

 Then you can remove the cluster surround containing the headlight switch, and wiper switches.  There will be three screws across the top of the surround and one in each corner on the bottom. Note that there will also be a smaller head screw near the larger body screw on the bottom of the gauge cluster surround.  This is for the switches themselves and it will not be necessary to remove them at this time.

 Next, pull the surround out slightly and reach around the back of the surround, there will be 3 or 4 plugs connected to the headlight switch, turn signal switch, wiper switch and cruise control switch (if equipped) that will need to be unplugged.  Once unplugged you will be able to slide the cluster surround and switches between the steering wheel and the dash.

 In some models it will also be necessary to remove the steering wheel, to remove the cluster surround.  If the cluster surround does not fit between the dash and the steering wheel, simply remove the two or three small screws on the back of the steering wheel to access the steering wheel nut.  Remove the nut, and rock the steering wheel or pull back sharply to pop the wheel off.  It is not recommended that you remove the steering wheel on vehicles equipped with airbags.

 Once the cluster surround with the switches is removed from the vehicle, you will remove the wiper switch itself. Pull off the buttons and knobs. Then remove the screws holding in the cruise control switch (or cruise control switch cover/blank) and the three screws holding the wiper switch. Pop the wiper switch out, by sliding it between the two sides of the cluster surround.

REMOVING THE WIPER RELAY 

Remove the wiper switch rear cover, by popping it loose with a small pick or flat head screwdriver at the two tabs on the back (plug) side of the wiper switch.  This allows you access to the rear of the circuit board of the switch.

Now you have two options that are dependent on your soldering skills.  You can unsolder the circuit board from the switch, or you can slot the front cover to access the relay. If you decide to go the solder route, you will remove the solder (with a solder sucker/remover or similar tool) from all the large tabs marked in red below:

Note: Some switches will not have the same number of large pins in the middle of the switch as they won't have rear wipers.  Shown here in red is the maximum number of pins that need to be de-soldered to remove the circuit board.

If you decide to go the slot method you will grind or file off only the top part of the housing of the switch.  Do not damage the sides of the housing, as it will weaken the housing and you may have problems with the circuit board cracking a year of two down the line.

Note: Generally we will do both, pull the circuit board and still slot the top of the housing, as the slot allows additional cool air to get to the relay to help prevent any further failures.

You will now be able to access the two or three relays (dependent on model) of the wiper switch. Relay 1 is the main front windshield wiper relay, Relay two is the front high/low speed relay and relay 3 (if equipped) is for the rear wiper.

Remove relay 1 by de-soldering its six pins (marked in red) shown below and pushing the relay back through the circuit board.  If you did not properly remove all the solder holding the relay on, the relay will stick and be difficult to remove.

You must be careful to not damage the circuit board or overheat the circuit boar when remove this relay and the solder holding it on. If you remove the relay, and small copper bushings are left on the pins of the relay, you have damaged the circuit board.  The copper bushings are from the circuit board being overheated and the solder not being properly removed.  Custom repair work will be required at that point that is beyond the scope of this article. For cars with rear wipers, it is recommended that you also remove the relay 3 marked with orange below.

The new relay(s) can now be inserted.  They only fit one direction, as the pins are asymmetrical. Carefully push the relay in and then while holding the relay tight against the board, solder the pins.  It is recommended that if you have a switch with a rear wiper, you also remove and replace the number 3 relay at the same time.

If you have removed the circuit board, now re-install it into the switch housing and solder the pins back in.  Snap the back cover on and you are ready to test.

 TESTING THE SWITCH  

Before re-assembly of the dash, take the switch over to the car and plug it into the correct harness.  Reconnect the NEGATIVE lead of the battery (if disconnected) and turn the ignition key to the On position.  You can now test the switch. It is fine if the other switches are not plugged in while testing.  Nothing will be damaged.

INSTALLATION  

If the switch tests out fine and all switch positions are now working correctly, you can pop on the back panel of the wiper switch, and re-install the switch into the cluster surround.  Then complete the repair by re-installing the cluster surround, plugging in all the switches and the steering wheel (if applicable) and steering column surround (if applicable).