'93 Camry LE V6 error codes 12, 55

[vibrosies]

Hello all,

Car: 93 Camry LE V6.

The CEL just came on. Shorting pins E1 and TE1 on the diagnostic port revealed codes 12 and 55.

The car still runs fine, I haven't noticed any change in performance. The timing belt was changed appox 2 months ago. Almost 180000kms on the car now.

I've found some discussion on code 12 in the forums here, but nothing on code 55.

Some info from Haynes Manual:

Code 12: RPM Signal - Diagnosis - no 'ne' signal to the ECM within several seconds after the engine is cranked...

Code 55: Knock control Signal (V6 engine RH bank) - diagnosis - problem with knock control system in ECM.

Any guesses at what could be wrong here? What does RH bank mean? Where do I start to troubleshoot this thing?

Thx in advance!

[Toysrme]

I was throwing 12 when I installed my SMT-6, doing ignition timing and the NE signal wire was cut.

NE is signal from the distributor (no crankshaft sensor) that tells the car what RPM the car is running. It could also be the G1/G2 signals from the distributor (thsoe are used to find TDC on pistn #1 and #6)
If there were really a problem with the NE signal, I promise. The car would not run if it didn't see it (period) and if there is a slight change in the signal, it will run very funny. If it was either the G1/G2 signals, it would run real funny at some point.
Haynes advices(in order) for NE:
Distributor Circuit
Distributor
Igniter
Igniter Circuit
Starter Circuit
ECU

You sound like you know what's going on b/c you've researched the codes. I honestly don't have any idea on the code 12. Check the distributor/ connector on the distributor. It wouldn't be the connector on the ECU because knock and ignition signals are not on the same connector. If either was loose it would obviously cause problems with tons of other systems, and you'd get tons of codes at once.

People will tell you the knock sensors are too sensative anyways. I say they're not an a 3vz-fe. I've done way advanced/retarded ignition timings that intrucuded bad knock into the motor and not seen the signal tampered with by the stock computer. (FYI mine knocks now b/c the timing is still way off, and it doesn't do anthing about it)

Cliff Notes:
Code 12 - Check & clean distributor harness, try a new distributor.
Code 55 - IMHO the stock sensors are not overly sensative, so maybe the sensor itself is bad, or the harness is dirty. Check & clean it also.


I've very intrested to find out what is causing the codes, 'cause it sounds real interesting to me if it's not a simple problem like a worn out part/electrical connection.

[vibrosies]

Well, here's what I did so far:

Investigating code 12
Checked the junction of the igniter wire that also feeds the tach signal to the remote starter. Connection is fine, solder looks good. I suspected that this junction might have corroded thus also affecting the RMP message to the ECM. I also measured the AC Volts at this junction and it seemed to be fine - going up and down following with the RPM.

I checked this junction because I noticed that while my car was running under remote starter, it killed the engine whenever I raised the RPM over approx 2000. And the remote starter gave an error code of "no tach" signal. I thought "bang" that's the whole problem! But as I mentioned, the AC Volts reading at the tach is good upto and over 2000.

I cut the tach feed to the remote starter thinking that it might somehow be loading the igniter circuit too much. Following this I cleared the codes and ran the engine. Surprisingly code 12 no longer appears! Sadly, however, I still get code 55.
It's still too early to tell if code 12 is cured, it might return and prove that the remote starter is not the cause. Time will tell.

Investigating code 55
Today I filled up with 91 octane, normally I run with 87. Let's see if this gets rid of code 55 - knock problem!

I do feel that the car has lost some power, especially in 1st gear. This might be the result of knock sensor / control circuit problem. According to the Haynes manual, these sensors are hard to get at. According the manual, to check them, one has to check the resistance of the center pin to the body (gnd). Resistance reading of 0 Ohms = faulty sensor.
I don't have the time/ or the experience to take off the intake manifold...gotta find an easier access point to check the reading on these sensors...

Will update you on any new developments... don't wanna take to repair shop just yet..gotta investigate this further. Afraid, that repair shop may overcharge in locating and fixing this problem.

[Qpats]

Vibrosies,

I also have the same code on my 92 Camry. It is a Camry SE.

The code is 55. Not sure what it means.

Did you get the problem fixed on your car? What was it finally?

Thanks!