Project88Turbo

iTrader: (22)

I've found two issues with my car:

FIRST ISSUE

Now that I finally have an intercooler, I took the car out for its maiden voyage.

The car pulled smoothly and boosted, but went into limp mode I'm assuming. I did not floor it, maybe half throttle. The check engine light came on and it would only accept small throttle inputs. Of course, shutting it off and restarting it would reset it until it did it again.

I attempted to check codes by grounding the TEN connector in the DIAGNOSIS box, but all it did was cause the CEL to light up SOLID. No flashing codes.

I found this thread https://www.rx7club.com/3rd-generati...codes-1014748/

But no real solution there. I'm assuming it's a bad connection somehow, but what color is that wire @ the ECU connector? I'm hoping that I can ground it at the ecu to pull codes, and then diagnose that particular wire as well.

SECOND ISSUE

This is a simpler issue to diagnose hopefully.

The headlamps do not go up when you turn on the headlamp switch. They do light up, and they do go up and down using the button on the dash.

Thanks in advance for the help!

Vince

wstrohm

First issue:

Here is a Diagnostic Connector diagram showing wire colors and their sources.

Second issue:

Here is the schematic of the headlight control system.

Project88Turbo

iTrader: (22)

^ You are the man!

Thank you for the links! I will post up when I fix it to help others that may search.

Vince

Project88Turbo

iTrader: (22)

OK. So I tried to diagnose the CEL issue.

I checked voltage @ the FEN pin in the diagnosis box and I get 12VDC @ KEYON then it drops to 1.65VDC after 3 seconds. This is not normal from what I've read. So looked at the wiring diagram to find it's connections. It Tees off to connector X-07 to go to the EL UNIT, which I could not locate, so I unplugged the EL UNIT itself.

This did not change the voltage readings @ the DIAGNOSIS box, but it disabled the CEL in the dash. So as a switch, I depinned 1F @ the PCM/ECU and plugged the EL UNIT back in. This resulted in 6.4VDC at the FEN connector.

Checking the now disconnected pin @ the PCM/ECU mirrored what the initial tests were: 12VDC initial then 1.65VDC afterwards.

SO, I have two theories:

1) There is an issue in the emissions harness that runs to the engine. I'm assuming I can unplug those connectors and if it is the problem, I should get about 4,000 codes if that is what was pulling the computer down.

2) The PCM/ECU is BAD! I have a POWER FC, but what would I be looking for on it that could tell me what is wrong?

Thanks for any and all help, I'm nearly out of options diagnostically.

Vince

wstrohm

Was this with the TEN -> GND jumper in the Diagnostic Connector in or out?

1) With the jumper in, the voltage on FEN should be low for 2-3 seconds, and then go high and stay there, unless there are stored fault codes, in which case the FEN voltage should rest high but pulse low to flash the CEL (per the codes). This is what our '94 does (1.8 v for 3 seconds, then 10.8 v).

2) With the jumper out, the FEN voltage should go low and stay there until engine start, i.e. that is a self-test of the CEL circuit that goes away at engine start. (Ours does that.)

3) You are right; the FEN signal routs to the Electrical Load Unit, which apparently contains a non-inverting buffer that drives the CEL bulb from its terminal "K." So it is also possible that the ELU's output voltage (orange wire with black stripe) might be shorted to ground instead of the FEN signal, which would also keep the CEL continuously ON. But in your case, your FEN voltage is not behaving correctly.

Project88Turbo

iTrader: (22)

Those tests were done with the TEN->GND jumper in.

When everything is hooked up and the jumper is out, it seems to operate properly.

KOEO: CEL = LIT
KOER: CEL = OFF
KOER in LIMP MODE: CEL = LIT

So, from my limited knowledge, the car is working as designed at this point. It has detected a fault, gone into limp mode, and illuminated the CEL to alert me to the problem if I was not aware of one.

But something is preventing it from telling me the code

When I get to it tomorrow after work I will try unplugging the engine harness @ the ECU/PCM and see if it allows the codes to display.

Am I proceeding correctly here?

When I did my previous testing, unplugging the #1 plug at the PCM to isolate the wiring, Neither the TEN or FEN connectors show continuity to GND or 12VDC+

Thanks for all your help!

Vince

Project88Turbo

iTrader: (22)

UPDATE!

I tried unplugging the two EMISSIONS harnesses. unplugging both results in no operation of the CEL.

Plugging the small only = NO CEL operation.

Plugging the large only = same CEL operation as before.

SO, either it is the PCM or it is the wiring. I am not about to depin one wire at a time and it potentially end up being the PCM anyway. So, I cut the 4 required wires and installed the Power FC. Car runs as designed now!

SECOND ISSUE = SOLVED!

I had two different issues here:

NO PARK LAMPS.
HEADLIGHTS DO NOT GO UP, BUT LIGHT UP.

Using the diagram above, I traced the problem to the RETRACTOR RELAY for the headlamps not going up. Jumping the terminals caused the headlamps to go up!

Checking the park lamps led to the TNS RELAY which is conveniently next to the above relay. Jumping the terminals caused the running lamps to operate!!

So, how did the relays fail??



They rusted!

Compared to one that was working:



New relays fixed both issues!

Vince