I've got a new group of engine codes, but the car is running great. Has anyone else had this grouping?

P1351 IC CIRCUIT HIGH VOLTAGE
P0336 CRANKSHAFT POSITION SENSOR A CIRCUIT RANGE/PERFORMANCE
P1371 TOO FEW LOW RESOLUTION PULSES
P1641 SERVICE LAMP CIRCUIT FAULT
P1642 AIR CONTROL CIRCUIT 3.4L

I recently had the PCM tuned by Solomon. Also, I think one of the cooling fans is hot wired into the fuse box. It was done before I purchased the car, but that's what it looks like. Its not running when the car is turned on anymore.

Any help is appreciated

 

Not sure where you dug up those code descriptions. Correct descriptions can be found here: http://shbox.com/1/Dtcs.htm Use the tabs as the bottom to select OBD type and options.

P1641 Fan Control (FC) relay 1 control circuit
P1642 Fan Control (FC) relay 2 and 3 control circuit

These two definitely because of your sketchy fan wiring.

The other three could be wiring problems or all related to opti issues. You might want to clear the codes and see what returns.

 

Thanks for the fast reply! These descriptions came from autozones code reader. The opti and ignition coil were both just replaced before my tune. Could the other codes be related to that? Maybe just needs clearing out like you suggested?

 

So, I bought a code scanner and cleared the existing codes. The ones that remain after a day of driving are: P1351 Ignition Control (IC) circuit high voltage (open circuit) P0336 Crankshaft Position (CKP) sensor circuit performance

The coil and optispark are new replacements. There's no obvious problem when the car is idling or driving.

 

What brand is the Opti?

Have you had the ICM tested, while hot?

P0336 for the crankshaft sensor sets when the PCM compares the signal from the CKP sensor and the signal from the Opti cam sensor. This shows if the cam is advanced or retarded. If they do not match, and the difference is greater than -10-deg to +7-deg, but within the range of -21-deg to +51-deg, DTC P0336 sets. That is telling you that the cam and crank are not correctly timed. This can be due to:

- poor harness connection at CKP sensor
- excessive timing chain wear
- mechanical distributor problem
- crank reluctor wheel damaged or incorrectly installed
- engine timing cover damage
- CKP sensor contacting reluctor wheel.

I have also diagnosed one case where this was caused because the Opti was not indexed correctly to the cam dowel pin.

The CKP sensor is only there for misfire detection. It does not affect how the engine runs. Even when the Opti was not indexed correctly, the owner did not feel there was any problem with the way the engine was running.

Can your scanner read "CKP:LoResolutionAngle"? That may be a GM "enhanced parameter," and not available on all scanners. You might need a Tech-2.

As far as P1351, the best thing to do is download the 1996 factory service manual (free courtesy of GaryDoug):

http://www.mediafire.com/?40mfgeoe4ctti

Look at the description of P01351 on page 6E-739 and follow the diagnostic logic chart. The code sets when the PCM detects a voltage greater than 4.6 volts on the white wire from the PCM to the ICM while starter is cranking the engine. Is the engine harder to start than usual?

 

I doubt I'll be able to solve the mystery of P1351. There's no obvious problem with starting. Is this something I can let slide or should it be addressed? As for P0336, it disappeared on the last code check, but the P1641 and P1642 reappeared. I'm thinking that P0336 is caused by the CKP sensor connection. I had a severe oil leak through the opti seal a while back and the CKP sensor is caked with oil.

 

One last time and I'll stop bothering you,

Did you have the ICM tested?

YES.... or....... NO.

What brand is the Opti?

 

The optispark is (GM05) $250. The ignition coil (E208Z) and ICM (CBE122Z) were replaced with the optispark last summer.

 

OK.... so the Opti BRAND would be a Spectra, $90 on Amazon. Not likely to be a reliable choice.

And, the ICM is new (didn’t mention you replaced it, only the coil and Opti). Were you getting these codes BEFORE those replacements (coil, ICM, Opti)? The fact a part has been replaced does not mean it is free of defects. The ICM needs to be tested.

 

Okay, I didn't realize I had the unreliable type of optispark. The car broke down after overheating and I was forced to take it a shop where they replaced all the above plus the water pump. Looks like I overpayed for it. After reading some reviews, it seems that brand of opti causes the P0336 and P1371 codes. I'm not sure if the P1351 was there before the new parts, so I'll have the ICM tested. Those fan relay codes are appearing occasionally.

 

As Rob/Shoebox mentioned in post #2, if a fan or both fans have been rewired incorrectly, that's causing the fan codes. He has diagrams on his website showing how to wire a fan switch correctly. Also has the factory wiring diagrams to show how they should be wired, without a fan switch.

http://shbox.com/1/fan_schematic_1995.jpg

All 1995-1997's and newer are wired with three relays, per the "late production" diagram.

http://shbox.com/1/fan_switch_wires.jpg

http://shbox.com/1/fan_sw_diagram2.jpg

 

Good News! All codes have been eliminated. The P1351 was fixed with a new, higher quality ICM. The one that was put during repairs at pepboys was a piece of junk. As it turns out, there was no faulty wiring to the fans, only wires for an accessory of some kind under the hood (not in use anymore). The P1641 and P1642 error codes were in conjuction with the typical air pump failure code. Anything air pump related with tuned out by solomon, so that one didn't show up. It was just the #7 fuse blown. As for P0336, I figure its related to the low quality optispark, based on the information I found. Its not there now, so maybe the new ICM will help.

 

My car is having hard starts now. Did that cheap ICM burn out the starter or is it more likely the cheaper brand optispark?

 

What are you see with the hard starts? Does it seem like the starter is having a hard time turning the engine, or is it just taking a lot of cranks to start?

If the prior, have the battery tested. If that pans out, have the starter tested.

If the later, start by inspecting plugs and wires.

 

After doing some extensive research, it seems that the low-quality opti-spark is the culprit behind the P0336 code. Others have reported low resolution codes like P1371, but I haven't seen that in a while. The P0336 comes on when I start my car, but doesn't reappear after I clear the code until another start or two. I have been lucky to not see the P1351 anymore after I put in a better quality ICM.