I just bought a 1990 rx7 na. It runs good, except for a few things. Only my headlights work for one. Searching here, said my problem lies with the headlight switch, switch harness or both. I pulled the gauge cover, its very messed up, all the upper screw holes are broke through the plastic, and saw one melted spot at a red wire, maybe 2nd or 3rd one up from the bottom. Guys at rx7.com said probably just the harness but i dont wanna order just the harness then figure i need a switch too, whatcha think? Also i have a check engine light. It comes on at start up, goes out for awhile then comes back on. I puchased a haynes service manual but it says take it to a dealer for diagnostic but id like to pull codes myself if possible. Theres alot of crap wiring for other stuff that was hooked up in the car that im trying to get rid of cause i know the computer is very sensitive to wrong wiring in the car from my last rx7 i had years and years ago. Also when i 1st fire it up, it seems to turn over a few more times than it needs to before it fires and when it does the rpms go really high, i spike the fuel pedal and it goes to normal. When its in gear at idle, the idle goes up and down alittle which also bugs me abit. So any advice I sure would appreciate it, and thanks alot. Getting new tires today.

 

With the headlight switch, the burned wire is a classic symptom. Replace both the harness and the switch.

There are instructions in the FAQ for pulling trouble codes.

The high cold start RPM is normal. It's to light off the precats. Tapping the pedal cancels it.

The wavering RPM is likely a vacuum leak and a maladjusted TPS. You may find a TPS code.

 

Alright, sounds good mr cake. I will check those things. Unfortunatly I didnt get a chance to read your post earlier, but i did exactly what you said. I got a harness and some new plugs from rx7.com. I found a used switch on ebay, and I ended up having to get another gauge bezel cause when i took out the screws, it just started to crumble apart. Ordered some new plugs with the harness as well. I'll dig into the facts and questions section you mentioned. If i can find it, lol. Still new to the forumn obviously. Thanks. Heres another question. My clock comes on when i 1st start the car but then goes out after its warmed up. If its been parked for awhile, same thing. And when it goes out, it always resets itself. Also the seat belt connector at the doors dont slide up and back. Fellow at rx7.com said those were recalled, but i wouldnt know how to see if they were ever fixed, i guess I gotta call a mazda dealership and give them my VIN? Anyways, thanks again.

 

Your seatbelts are under a lifetime warranty by Mazda. The dealer will fix them for free.

As for the clock, you need to pull the clock/idiot light module and resolder it.

 

ok, i will do that. i have acuople new questions, i have to start a new thread as its not related to this one, thanks.

 

Alright, i adjusted the tps. Theres alot of confusion in these threads as to which way is the best. I just probed the green/red wire and adj to 1v. Didnt seem to change anything though. Idle still surges up and down from say 800 to 1200 with the clutch pushed in and in gear and only settles at about 1000 without. Also pulled my codes and got an 11. Intake air thermosensor. What is it, where is it and how to i replace it? Thanks.

 

The IAT is located on the passenger side of the intake manifold, down near the front. The connector has no lock on it so it may just be disconnected.

Use the ohmmeter method of adjusting the TPS as in the Haynes manual.

Make absolutely sure there are no vacuum leaks. Also, the hard idle screw may have been played with at some point. If you are absolutely sure there are no vacuum leaks, you can adjust the idle as per the instructions in the FSM.

 

Thanks again mr cake. I did find the sensor on here and it shows it screws into the intake on the drivers side near the firewall. Is this incorrect? Also, my haynes manual doesnt show me how to adjust the tps, codes, or any of that. It just says its to much for the do it yourself guys and it has to be taken to a dealer or mechanic that has the right equipment. Im finding this haynes manual to be a terd of a service manual. I cant even find how to remove the rear taillamps in it. Only reason im looking for that is because i have one lens that doesnt lay quite flat like the other. Theres no cracks or anything of the sort, but i just was trying to figure out if its a 2 part lens so to speak so i could take it off, squeeze it back together to get it to set in flush like the other.

 

The engine needs to be idling at 750 rpm or so before you turn the car off so the TPS could be adjusted to 1 volt w/key t on. Adjusting the TPS screw before the engine is fully warm will lead to a faulty adjustment so if you did not fully warm up the engine back to the drawing board and do it again.

The wire connected to your IAT should be Green. Is yours?

 

I had the car at full operating temp as it stated to do so in the info provided here before i probed the green/red wire to adjust the tps. And if the intake air thermosensor is the same as the iat, and its the one at the firewall on the drivers side, then it has 2 wires. Small white plug that plugs on the screw in sensor with 2 prongs. One wire is green and one wire is brown/black.

 

That is your Intake Air Thermosensor. And if you look in the FSM it will show you what voltage value it should read at the ECU w/key to on.

EDIT: Pin 2L (Green wire) should read 1 -2 volts w/key to on and engine warmed up to 176 degrees.

 

Ok, gotcha. I mean thats the error code im getting is 11. So thats the thermosensor and Im looking at the correct sensor yes? Which is not the same as the other sensor mr cake was trying to direct me to, yes? Im just going to replace the sensor. Thanks for the help.

 

On an S5 the IAT has the two wires running to it that you described. A code #11 is for the IAT on an S5. I'm familiar w/the S4's and not S5's, so where it's located is a puzzle to me unless I looked in the FSM, which is something you can do.

 

ok, thanks, yes, i believe i found it. I gotta call mazmart tomorrow bout parts.

 

Have you checked the Green Wire at the ECU yet? The sensor might be fine, but the connection or wiring could be at fault and there would be no reason to replace it until you're certain that the the fault is from the sensor and nothing else.

 

Turns out I have some kind of mixed and matched wiring harness. I spoke with chris at rx7 and he said it is possible to use parts from both harnesses and get it to work properly. I bought a new subharness and a used headlight switch. Put the subharness in, got the switch today, hooked that up and presto, fried the switch I just got. So after speaking with chris, best case scenerio, was i had to repin and match the new subharness as to match the old one. Did that, out of light now, so ill try hooking it up tomorrow after work and see how much is left of the switch I just got. Probably have to send it to rx7 and have them fix it. Unless i can find another used one. But now the question is, a switch for an 86-88 or 89-92? Also how can i figure out what year the cpu and what year ecu i have? Thanks. Im so pissed off right now i dont even have the words.

 

That sucks. I don't know a way off hand to glace at the harnesses and tell what year they are, other than comparing the wiring using the FSM. Switches are different from S4 to S5 for sure.

 

Well, i do have another switch on its way, its off a 90. Chris said either switch will work. If not im sending him my old harness and both if not all 3 switches, and he'll make one work for me. I did repin the new harness, plugged it in, held my breath and plugged in the switch i fried to see what i did to it. I ended up with no headlight or illumination function but my parking lamps and tail lamps work, complete opposite of the original, why i was replacing. So far, ive had it for a week and a half, i drove it home. Im hoping after i get this switch, and the thermosensor and seatbelts in, i can fix those things and everything will be smooth after that. When its said and done, ill have had gotten 2 switches, a new subharness, thermosensor, gauge bezel(mine crumbled to pieces when i took it off for the switches), plugs, hlf a dozen fuses, lol, tires, and a cool pioneer walmart special stereo. Then i can do stuff as i go along, like cleaning up the sunroof so it opens and closes abit better, make me a cold air intake, the cool stuff i can do and take my time with.