'94 Celica 5S-FE M/T ECM pin connections

[gidbud]

I have a ’94 Celica GT, manual transmission, 5S-FE engine. My problem is a FI1606 code. According to the manual:

Diagnosis:
(7) No NE signal is input to ECU for 2 secs. or more after STA turns ON.
(2) No G signal is input to ECU for 3 secs. or more between 600 – 4,000 rpm.


Trouble area:

• Open or short in NE, G circuit
• Distributor
• Open or short in STA circuit
• ECU

The engine runs GREAT. I drive it to work 30+ miles every day. The only problem is that I cannot get an inspection sticker (Texas) with the check engine light on. BTW, I’m beginning to think that little light should be called the money-maker light for all the $$$ I have paid to the auto repair stores.

I have replaced the distributor 3 times and repaired the ECM twice. I’m getting perfect continuity on the NE and G circuits, so I know the drawing is correct for those wires. The primary and secondary coil resistance readings are all in specification. All that is left is the STA circuit. My problem is that the drawing for the ECM connection for the 5S-FE M/T does not seem to match the real thing. Please see the picture of my ECM connector with the drawing of the ECM superimposed in the link below. The drawing is from page FI-92 in the Toyota Fuel Injection manual.

http://farm3.static.flickr.com/2618/4209099079_b72c9a3aea_b.jpg

The slot for the STA wire is vacant! Just to see if I could figure this out, I checked each wire in the connector while turning the key to ‘Start’ (clutch pedal depressed), but none of the wires changed voltage when I did that. What that tells me is that I could have an open STA circuit, but which wire is it?!

Anyone have a clue as to which wire it could be?

-Gidbud

[gidbud]

I figured out that, according to the Toyota wiring manual, the connectors on my GT match the connectors for an automatic GT. Mine is DEFINITELY a manual. With that mystery solved, I was able to locate the STA circuit and it does not have any issues. I'm not sure why my connectors are A/T connectors. As far as I can tell, this car has always had a manual trany, and there are no splices or any indication that someone did a re-wire at some point. Perhaps Toyota changed the wiring in '95 (my manual is for the '92).

I continue to drive it to work every day. It is MUCH cheaper than the Suburb. 25+ MPG vs. 16 MPG. I cannot get an inspection sticker because of that silly check engine light. I risk getting a ticket for an expired sticker, but even that is cheaper than gas.

So, my mystery remains: why am I getting an FI1606 code when all of the required tests are within specification?

I appreciate both of my readers!

[tomtom25]

there could possibly be a TSB out for that problem. The picture of the connector doesn't look like the correct one for the connector you are looking at! Alot of the time though there is a TSB out for that problem.

[Gohan587]

sorry to revive this thread.. but my car is having these exact symptoms.. just wondering if/how your problem has been fixed?

[gidbud]

Gohan587,

Man, I'm sorry you are having the same trouble. I never did find the root cause of the FI1606 error. I took it to the dealer and they were very cooperative and did the code read for free, but all they told me was what they read out of the manual. I had to get the car inspected (Texas), so I took out the dash and snipped the little wire leading to the engine light, backed away from the car and let the feelings of appropriate guilt pass, and took it in for an inspection. I now have a "legal", clean burning, somewhat dependable vehicle to drive to work every day.

I did splice on a leader to the wire I cut just in case I wanted to connect a bulb to it to read the blink code. That way I don't have to tear the dash apart again.

Good luck with your car. Maybe if you find a better solution you can update this thread. :-)

-Gidbud

[Gohan587]

i appreciate the response.. its unfortunate that this problem hasnt been resolved yet. I'm still trying to figure out what exactly might be causing this problem.. i have a few more tests to do before i decide on getting a whole new distributor housing.

so does your car begin to hiccup after a few minutes of driving aswell?

[gidbud]

My car does not hiccup. It runs perfectly. That is why I went ahead and clipped the wire to the engine light. Must be something in the ECU that the ECU repair shop cannot find. I dunno. It runs, so I am happy.

I would recommend getting a new distributor assembly. That way you can rule out that as the cause.

[Gohan587]

yep.. thats my next plan. Once that is done, if CEL stays on, then i will just have to ignore the light. thanks again for your input.