1986-1991 RX-7
Solutions

[CPU Cold Solder] [3800 RPM Hesitation] [Clock/Light Colder Solder] [Logicon Colder Solder] [Intermittent Speaker] [Catalytic Converter] [Rear Suspension Clunk] [Notchy Shifting into 3rd Gear] [Broken Outside Door Handles] [Rusted Exterior Window Trim] [Broken Seat Lever] [Failing Light Switch] [Failing Wiper Switch] [Shift Lever Bushings]



CPU Cold Solder Points Fix
-- David Disney
(Older version by Don St.John)




It is a good idea to disconnect your battery when doing any kind of electrical work on your car. When resoldering these circuit boards, don't use a mega-huge, three million watt soldering iron. You'll just end up making a mess. The usual five dollar R adio Shack soldering irons work just fine. Also, if you have never soldered before, you'd better get some practice before you delve into your beloved Rx-7's CPU.
  1. Remove the Driver's Side Kickrail. (The long plastic piece that mounts immediately below the door. After removing all of the screws in the kickrail (there are four or five), you must pop the kickrail up, away from the vehicle. There are several metal clips under the kickrail that hold it down, so you will
  2. Have to provide a pretty good amount of upward pressure, but be careful that you don't pull too hard on either end of the rail or it could break. I haven't broken one yet (they seem to be pretty tough), but I'm sure it can happen.
  3. Remove Plastic Side Panel. Take a look at the plastic side panel on the left side of the driver's footwell. You will have to use a pair of needle nose pliers to remove the three plastic inserts that hold the panel in. Just pull 'em out. Then m ove the panel out of your way.
  4. Unplug the CPU Wiring Connectors. Now you should be able to see the CPU. Its the rectangular box that has a big wiring harness plugged into the front of it. Unplug the 'big wiring harness' I just mentioned.
  5. Remove the CPU Restraints. Now you'll need a 10mm socket and a short extension. A ratchet would be a good idea also (unless you have really strong fingers). At the top of the CPU is the nut that holds it in. Remove the nut.
  6. Remove the CPU. Now you should be able to tilt the top of the CPU towards the passenger's side of the car while pulling upward on it. The CPU should pop right out. Notice how the protrusion on the bottom of the CPU fits into a little socket in the car. You'll need to realize how it fits when you
  7. Put the CPU back in. There are also a couple more wiring harness connectors on the bottom of the CPU, unplug these also. Now you have the CPU out of the car. Take it inside and plug up your soldering iron.
  8. Start Taking it Apart. There are two small screws on the outside of the CPU case. One is on the bottom and the other is on the back. Remove these screws.
  9. Remove the CPU Case. Now you will have to take a small screwdriver and pry the back lid off the CPU case. Also pry the bottom of the case off. You will have to be very careful and patient so that you don't break the case. After getting these covers off, you can remove the circuit boards from the case.
  10. Resolder the Beastie. Take a close look at all the solder points on all three of the circuit boards. It would be wise to resolder all of them. However, if you're in a hurry you can just resolder the areas where the spade connectors for the wiri ng harness plugs are located. These are easy to recognize because of the copper spade connectors on the component side of the board and the larger solder points (Figure 5) on the other side of the board. These solder points seem to be the main cause of trouble because they are under the most stress from the weight of the wiring harness bouncing around on them. They're almost always cracked and should get most of your attention.
  11. Put it Back Together. What is it all the shop manuals say? Oh yeah, installation is the reverse of removal. Just put everything back together and you should be in great shape!


3800 RPM Hesitation Fix
-- Dana Sullivan


    |                   |    |------upper left wire should be brown
    |      ________     |  ''|=='''
    |---   |      |  ---|  | -  - |  This is supposed to look like
    | o |  | 13B  | | o |  |'-''-'|  the plug you disconnect from the
    |-#-   |      |  ---|            sensor.
    |   \  |______|     |            Take the upper left wire, brown
    |    boost sensor   |            with black stripe, ground it to
    |___________________|            the radiator filler neck.
        front of car
  1. Locate the boost sensor on the front of the passenger's side strut tower. Note: There is a vacuum line running from the sensor to the side of the engine block.
  2. Disconnect the 4­wire 'gang plug' from the sensor.
  3. Locate the upper left wire. Refer to diagram.
  4. Take a very small flathead screwdriver and insert it into the back of the plug on top of the wire. You should be able to raise a small flap of plastic allowing the brown wire with it's crimped connector still attached to be removed from the gang plug.
  5. Take a 12" piece of thin gauge wire and solder one end to the connector where it is crimped around the brown wire.
  6. Insert the crimped connector with the new wire attached back in the gang plug.
  7. Loosen one of the bolts that holds the radiator cap housing to the filler neck. Strip ¾" of wire off the end of the ground wire your just soldered and wrap it around the loose bolt. Tighten bolt.
  8. Plug gang plug back into boost sensor


EDITOR's NOTE: This fix is NOT guaranteed, it seems to have about a 50% chance of solving your problem. It does NOT work on my 1987 Sport, but others have had success with it. I personally do not think this is the cause of the problem. I believe, partially because it worsens in low temperatures, that it has to do with wear on one or more other components, or a programming error in the engine management computer. I happen to know of one 1987 GXL of a newer build date than mine which does not suffer from this problem. I believe that the problem may be caused by progressive failure of the exhaust system. I think that as the exhaust gets older and the front cats start to disintegrate into the main cat backpressure increases, causing the ports to open early or late. When I replaced the cats on my car with a downpipe and presilencer from MazdaTrix the problem promptly vanished.


Cold Solder Points Fix For The Clock/Idiot Light
-- Tuck



Start by placing the blade of a flathead screwdriver under the front lip of the plastic trim piece that is in front of the clock/idiot light unit. Pry it up and you will see two screws that hold the assembly in place, one on each side of the unit. Remove these screws and pull the clock unit out. The wires are tight but some slack can be pulled out from the inside of the dash. Unhook the clock/idiot light module. Remove a few screws from the back of the unit and carefully check and resolder all the solder connections on the socket for the plug. Resolder other stuff if you are feeling adventurous. Installation consists of plugging the unit back into the wiring harness, screwing it back in, and snapping the trim piece back over the unit. It is short and sweet. One important note, if you decide to resolder ALL of the solder points in the unit, be careful, there are a number of delicate components that can be killed with great ease by overheating, especially under that little black plastic thing.


Cold Solder Points in the Logicon
-- Mike Mario



I have repaired my logicon because my heater didn't maintain the correct temp. It would stay hot for a while and then the air mix motor would move the vent settings to the cold position. It would generally stay in that position. There is also another well known problem with the air mix adjust motors. They were manufactured with an inappropriate lubricant, which causes the motor to seize in low temperature environments. This can burn out the drive transistors in the logicon and possibly the motor itself. As a rule, if you took your car to the dealer because of logicon problems they replaced the air mix motor whether you liked or not.

My air mix motor was not the problem in my case, I even took the logicon out and tracked down the drive transistors and replace them to no avail.

To repair the logicon, all the solder joints need to be resoldered. There are 3 circuit boards in the logicon, a large main one, one behind the front panel switches and lights and one in a small separate box attached to the outside.

The problem in repairing the logicon is not the actual resoldering but rather getting the logicon out of the dash. It is fairly straightforward to take the logicon apart and get at the circuit boards.

To take the logicon out of the car, you first need to take the cover off the center cockpit console. First pop up the cover around the shifter, this is done by prying it up from the side toward the hand brake. This exposes 2 screws under the ash tray. Remove these screws and then remove two more screws at the very top of the trim panel.

The logicon is held in place with 4 screws two on each side. There are three connectors which need to be removed, two are connectors that plug into the back of the logicon and are reasonably easy to remove. The third is the big problem.

The third connector is at the end of an 18" cable which comes out from the logicon itself (why they did this I'll never figure out) it snakes up into the dash and disappears. It ends at a connector which is where the windshield meets the dash behind the clock/light module. There is a metal plate running the length of the dash along the window, you need to remove this plate to get at the connector.

To remove the plate (while minimizing the possibility of damaging the trim pieces) requires that you remove much of the trim around the front window. Start at the top and remove the side molding on one side of the window (you will need to remove the center trim piece on top of the window to do this easily). Now you can lift out the metal plate which contains the defrost vents and spans the dash from window pillar to window pillar. It is fastened down with a screw at the center which is covered by a small square plastic cover (which is extremely difficult to get off without breaking), and a number of strong snap in metal clips. After removing the screw the rest of the plate pops off. You will have to carefully maneuver the plate to get it out once it is unscrewed and unsnapped.

Now you can disconnect the connector and pull out the logicon. The cable going the connector is held in place by a metal strap in the middle of the dash, you may be able to get at the strap to bend it up from the opening made by the metal plate. I originally loosened the strap from below as I was removing the air mix motor.

Remove the logicon from the dash while carefully snaking the long cable out from behind the dash. Once you have done this it is a fairly straightforward process to disassemble the logicon and resolder the points inside. Almost all of them will be bad so plan on spending some time on this. You may want to source some replacement light bulbs for the lighting instruments in the faceplate (not the LED's in the sliders) so that you can replace them while the unit is out. When you are done, you may want to spray the boards with a clear enamel which is sold at electronics stores for sealing circuit boards. Reinstallation is much easier than getting it out, and once you have removed the unit once, subsequent removal is much easier.


NOTE: If your Logicon fries and you decide to pull it and fix it yourself, use a transistor checker. If the transistors appear to be fried then you might want to consider getting a new adjust motor before you replace/fix it. MazdaTrix stocks rebuilt logicons for $231 the part number is "LOGICON" and MazdaTrix can be reached at (310)­426­7960. I believe they can also sell you the bulbs inside the unit.


Intermittent Operation of the Passenger Side Speaker
-- Victor Bradley



My 86 RX-7 had a Front right speaker that would go dead every now & then. When I whacked it with my palm, it would work for awhile, until I went over my next bump. Now I know what you're thinking... cold solder joint, right? WRONG! Bad relay inside the speaker box. Here's how to fix it. Remove the speaker box, unplug it. (Make sure the radio is turned off first.) Open it up and look for a little black plastic box on the circuit board that's located just inside the rear cover just inside the box from where the main connector plug is. This little plastic box is a relay. The top pulls right off. Now you can watch the stupid thing turn on and off when you flex the circuit board. If it does as I've described, the fix is simple: just jam a short piece of a toothpick, or any other small insulator into the mechanism so that the relay points stay closed. This fixed it for me.


Catalytic Converter Shield Fix
-- Tuck



In my case, the front hangar has rusted out, and the shield was making a nice road kill scoop/gravel plow. Go to your local Trak Auto (or similar store, such as Auto Zone), and ask for a catalytic converter hangar. They sell them for a few bucks and they are perfectly adequate for the job. It took me all of 8 minutes to install two in my car (one on the front and one on the rear of my cat shield). The vast majority of this time was spent jacking the car up. All you have to do is wrap it around the cat and the shield, pull it tight and then screw it down. This is a much better fix than getting new parts from Mazda, as you have to buy a whole new catalytic converter to get the hangars ($900).


Clunk in Rear Suspension
-- Jay Harrell



Replace the rear control links.


Notchy Shifting into 3rdGear
-- Anonymous



This problem is caused by weak synchros in the Mazda 5 speed, it appears that the 5 speed used in the non turbo cars is approaching it's power handling limit. To completely solve this problem requires a transmission rebuild, but if you don't want to spend the money or the time, you can at least smooth things out a little bit by filling your transmission with RedLine synthetic lubricant. Some people have expressed concerns over using the RedLine MTL because it has a lower viscosity than the stock lubricant. It's your call as to whether you use RedLine synthetics or their MTL. If that doesn't do it, get your transmission rebuilt, be aware that parts costs in this case can easily exceed labor costs. You can contact RedLine at 1­800­624­7958.


Broken Outside Door Handles
-- Ken



Your best bet is to acquire a new handle from MazdaTrix, or from a junk yards and getting it painted to match by a competent auto body shop. Otherwise you may be able to fix the problem by opening up the door and using JBweld, or liquid weld, or whichever is your favorite metal repair chemical to fix any cracking in the metal of the handle frame.


Rusted Exterior Window Trim
-- Chuck Ortt



Snap off the plastic trim piece around the manual mirror adjust lever. Unscrew the mirror mounting screws. Pop out the original piece and replace with the Mazda replacement part (which is plastic). Put it all back together.


Broken driver's side seat adjust lever
-- Anonymous



This problem involves the plastic trim piece on the door side of the seat. This trim piece comes loose and can jam the adjust lever. The lever itself is a metal piece with a hole in it. There is a metal post on the seat adjust mechanism that is supposed to go into this hole. The retaining clip on the post fails and the lever pops off the post, causing the seat to continuously spring forward (and pushes the plastic mechanism cover out). If you remove the spring on the lever, then the seat will no longer pop forward, but the lever then has to be pushed back down manually to lock the seat in place. The only other solution is to replace the retaining clip and trim piece, or to replace the rails and adjust mechanism on the seat.


Failing Light Switch
-- Anonymous



Replace the light switch assembly, this is due to a non­correctable mechanical failure in the switch. Please closely examine the plugs on the light switch, as this problem is usually accompanied by high voltages that melt the switch, plugs, and sometimes the wiring harness. If this is the case, replace the light switch wiring harness as well. The wiring harness and switch are available from MazdaTrix. The part number for the switch is "66­1700­FB01" and the harness is "66­1670­FB01". The switch is $225.30 and the harness is $65.75. MazdaTrix can be reached at (310)­426­7960. These parts can usually be acquired very cheaply at a junk yard. You can help prevent this problem from afflicting your car by disassembling the unit and resoldering everything inside it prior to failure.


Failing Wiper Switch
-- Gary



First remove the binnacle that contains the switches, unplug the 3 large connectors, and take the unit in to the workbench for a close examination. Remove the wiper switch module by pulling the knobs off and unscrewing the 2 screws that secure the module to the plastic binnacle. Then lever off the white plastic cover over the circuit board (it is secured by tongues into the black plastic case). Then desolder the rows of pins that secure the circuit board to the three switches in the module and remove the circuit board. Now, lever the cover off the relay nearest the wiper switch end (careful, these relays are fragile inside) and examine the open contact, it may appear burnt. Dressed it up with some fine emery paper, gently push the outer fixed contact in a little to close the gap a fraction, and reassemble the whole mess. Viola! Your problem is solved.

The tricky part is identifying the pins of the switches that need to be desoldered to get the PCB out. They are all along the "inside" edge, in two rows clustered in three groups (about 14 contacts in all). One of the wiper switch contacts is particularly difficult to desolder, as there are two pins shoved through the same hole. Use Dri-wick (solderwick) or similar, unless you have desoldering equipment at hand. Use only a hot enough iron to do the job, too much heat will cause the tracks to lift off.

The switch is, of course, also available from MazdaTrix, and can be purchased very cheaply at a junk yard.


Replacing Worn Out Shift Lever Bushings
-- David Disney and Jamey Moss



The following info is for 86-88 Sevens, but the process is almost identical for the 1st gens, but some of the part numbers/bushings are different.

First, obtain some new shifter bushings. I'd suggest getting them from MazdaTrix, as your local dealer will charge you 2-3 times more, depending on the day of the week... and they won't have them in stock either. Anyway, the MazdaTrix part numbers are as follows:
99-1780-M505 ~$6.50
17-4810-8AF1 ~$6.50
1-800-426-TRIX

Next, you have to get to the old bushings:

  1. There is a locknut just below the shifter knob. Take an adjustable wrench and turn it clockwise. The knob should now be lose and you can remove it and the locknut.
  2. CAREFULLY pop off the shifter cover panel. It contains the leather boot and pops straight up as one piece. If you are not careful you will break the tabs off the panel. Also, do not pull on the leather boot...bad idea.
  3. Now you can take a 10mm socket and a short extension and remove the 3 bolts that hold the shifter to the transmission. You may have to fish around in the myriad of rubber boots to get at them, but have patience and you'll be ok. After removing the 3 bolts, apply moderate upward pressure to the shifter lever. It is held in to its socket by a spring, so you may have to wiggle it a bit while you pull up on it.
  4. So, now you should see the plastic bushings (or what's left of them). I would suggest fishing any chunks of old bushing out of the shifter housing.
  5. Now you can look at the old bushing setup and get a good idea how the new ones should go. Its something like this: On the bottom of the shifter 'ball' there should be (going from bottom up) a spring washer, possibly another thin washer, and finally the plastic cup that the 'ball' sits it. On the top of the 'ball' they go in the opposite order. The tricky part is the top. You'll have to _carefully_ remove the rubber boot so that you can slide the bushing down over the shifter lever. I find that some Windex helps grease things up.
  6. Assembly is the reverse of installation (duh, where have I heard that before?). When you put the shifter back in, be sure that the little notches in the 'ball' cups (no laughing!) line up with the slot in the shifter ball and the little knob in the shifter housing.
  7. Put everything back together and you're done!


NOTES: You won't use all of the stuff that comes in the previously listed parts kits. Mazda apparently decided not to make a single 86-88 bushing kit, so you have to 'make your own' from these two kits. The parts to use are as follows:

  1. Keep the blue bushing, the white bushing, one spring (the round metal piece with clips), and one gasket.
  2. Next, put the blue bushing on over the shifter with the rounded side of the bushing next to the large ball part of the shifter.
  3. Clip the spring to the white bushing (it only goes on one way), then put the white bushing, spring-side down, into the hole where the shifter goes, aligning the grooved part of the bushing with the aligning pin in the hole.


Visitor