View Full Version : Caddy techs- need some help here


M Jarve
08-28-2010, 04:57 PM
As some know, I have a '97 DeVille I got not too long ago. I just drove down to the grocery store, and when I came out and started the car, it would not start right up. I cranked it a few times, during which it seemed like it was not firing except the occasional rumble. After about 10 seconds of cranking, it finally fired up.

The check engine light came on, and the DIC showed 0RPM, even though the engine was running. I drove home (about 10 blocks)- noted that it does not have quite the same "pep" as it did just 15 minutes earlier- and parked. I tried starting it again, and it was the same thing.

I remembered how to pull the trouble codes, and did so. Three came up (aside from some related to the TCS/ABS that have been there forever).

PCM P1350 CURRENT
PCM P1375 CURRENT
PCM P0603 CURRENT

The symptoms seem to be hard (but eventual) starting, and not quite the same power.

I tried looking up the trouble codes, but only came up with a bunch of sites selling either an OBD tool or a service manual.

Any thoughts, or anything I should be looking at?

Thanks!

Ed in Tx
08-28-2010, 05:05 PM
You can cneck those DTC codes here http://www.iequus.com/Dtc


P1350 - Ignition Control System

P1375 - 24X Reference Voltage Too High

P0603 - Powertrain Control Module Keep Alive Memory (KAM) Error

skippy_ps
08-28-2010, 05:58 PM
Google "cadillac p1350" and so on and you'll get some better results. Info at cadillacforums.com popped right up.

Good luck!

Murray

M Jarve
08-28-2010, 06:35 PM
Thanks for the link. Unfortunately, it seems I have a whole host of potential problems to choose from- from bad ECU to corroded contacts on the ICM. I did notice that when I jiggled the big wire harness around that the engine idle changed a little (perked up), but since I was in the engine bay, I didn't get to see if maybe the RPM's came up or not.

But, on the bright side, it seems to be one of those issues I can live with as long as I can live with it.

kx250rider
08-29-2010, 12:44 PM
I'd have the fuel pressure checked first. I believe that if the pump is failing, it can cause all kinds of codes to come up, and it will cause hard starting, loss of power, and MAF & O2 sensor fail codes. Especially if the car was running fine, and this happened all of a sudden.

Again, not an expert here, but a Caddy lover with open ears and paying attention to reading things over the years on Cadillac sites.

Charles

bentpencil
08-29-2010, 02:19 PM
I did notice that when I jiggled the big wire harness around that the engine idle changed a little (perked up),

Contact cleaner on harness plugs is a cheap thing to eliminate.:thmbsp:

M Jarve
08-30-2010, 10:57 AM
I tried a contact cleaner (containing, among other things Deoxit DL100), on the connections going to the ICM and the corroded grounding strap- no dice, but I did manage to break one of the connector locks.

But, I think I'm on to something... One thing I noticed the day after the initial posting is that everything was normal when the engine was cool, especially if the car had not been run yet that day- the "fun" started once the engine was warmed up, specifically when the thermostat opened.

It looks like there is a metal cooling pipe that goes from one side of the engine to the other. At some point in the past it was bypassed with a rubber hose, and whoever did this zip-tied the hose right to the wiring harness!

Well, I've moved the hose well away from the harness, and wrapped the harness in aluminum tape in an effort to keep it cooler. We'll see how that goes. I would really, really hate to have to tear that harness apart and taping up wires. Hopefully this fixes it (or at least makes the problem go away).

coffee123
09-03-2010, 08:00 PM
Harnesses are problems on those cars, as are bad grounds....however usually with the hard start youll need a fuel pressure gauge to check...but fuel pressure regulators and pumps go bad.

Mark

M Jarve
09-04-2010, 07:31 PM
It seems I'm doomed. It starts normally in the morning, or if it's been sitting for four or five hours, showing RPM's, starts right up, etc. Run it for about 5-10 minutes, to work, for example, and it goes goofy again- if I'm stopped when it happens, it stalls out; if I'm moving, it stutters but keeps going. When it does this, if I hit the accelerator hard, it kind of revs up in steps, but will rev up- also, going down the highway, it goes like a bat out of hell, but takes a bit to get there, accelerating in steps, sort of an alternating surge and plateau.

Does that help narrow it down? I hesitate to think it's the fuel pump, as I don't think it would reliably (albeit slowly) rev up or accelerate without hiccuping.

skippy_ps
09-04-2010, 07:52 PM
P0603 is loss of long term memory likely due to the ecm or battery being disconnected. I'd clear that one and see if it comes back. I have an Actron OBD2 scanner that I bought a few years ago and it paid for itself the first time I used it.

If it does come back, you're losing power to the ecm and should be pretty easy to chase down. More in a minute.

Murray

skippy_ps
09-04-2010, 07:56 PM
P1350:

Re: p1375 icm 24x reference voltage too high and p1350 ignition control system

DTC P1375 IC 24X Reference Circuit High Voltage
Refer to Cell 20: Ignition Control (IC) Module in Engine Controls Schematics.

Circuit Description
This diagnostic test checks for 24X signal at a logic high condition. The fault could be induced by the failure of either Crankshaft Position A or B Sensor input signal to the Ignition Control Module. Under such a condition, the Ignition Control Module would force the 24X signal high. This DTC will also set if the 24X signal is shorted to voltage externally. If either condition is met DTC P1375 is set.

Conditions for Running the DTC
DTC P1376 is not set.
Engine speed greater than 496 RPM.
At least 7 CAM pulses received since key ON.
Conditions for Setting the DTC
24X signal voltage is high and no 24X reference pulses have been received during the last 8 4X reference pulses.

Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.
Conditions for Clearing the MIL/DTC

The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.
Use a scan tool to clear DTCs.
Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.

Checking for a faulty crank A sensor or circuit failure.

Checking for a faulty crank B sensor or circuit failure.

To ensure acuurate voltage readings, connect the DMM J 39200 to the sensor before recording the Peak Min Max voltage.

To ensure acuurate voltage readings, connect the DMM J 39200 to the sensor before recording the Peak Min Max voltage.

skippy_ps
09-04-2010, 07:58 PM
Re: p1375 icm 24x reference voltage too high and p1350 ignition control system

Crankshaft Position Sensor (CKP) A is the lower, B is the upper. Both are next to each other, vertically, just to the right of the oil filter adapter. Up on the front side of the engine. The knock sensor is up in the engine intake valley

To do the job properly with few tools and little experience, the car should be up on a lift. Remove the lower splash shield and look up and in with a good drop light. If you're clever and have the tools, you can change the 2 CKP's without removing the oil filter, hoses, and adapter, but that process gives you more room. Each CKP (they're different) has a unique electrical connector so the wires can't be mixed up, but the sensor must be placed in the proper opening. You may have to go to the dealer later in order to have the CKP Relearn procedure done if there's a low speed driveability problem.

Go into www.rockauto.com and drill down to your car and year, engine and/or emissions/ modules in the drop down menu and find "Crankshaft Position Sensor". Also get 12-14 of the plastic pop rivets for the splash shield from a GM dealer. $.50 or so each. If your car has an oil cooler (2 pipes coming out the front of the oil filter adapter) you also need new quick connect fittings which screw into the adapter.

Total DIY: $110. Total dealer: about $475.

skippy_ps
09-04-2010, 08:03 PM
The stuff in posts 11 and 12 comes from cadillacforums.com.

Sounds like crank sensors need to be replaced. For $100 - $200 in parts, I'd jump on it although it sounds like a pita to change them. I guess I'd make sure the connectors were clean and tight and the wiring back up to the top of the engine looks good first.

Keep in mind that I'm just gathering info like I would if it was my car. I ain't no pro mechanic, that's for sure.

Murray

Jailtime
09-05-2010, 12:38 AM
The stuff in posts 11 and 12 comes from cadillacforums.com.

Sounds like crank sensors need to be replaced. For $100 - $200 in parts, I'd jump on it although it sounds like a pita to change them. I guess I'd make sure the connectors were clean and tight and the wiring back up to the top of the engine looks good first.

Keep in mind that I'm just gathering info like I would if it was my car. I ain't no pro mechanic, that's for sure.

Murray

CadillacForums - second best site on the Internet! :yes:

I'm with you on replacing the CKPs. Definitely a problem spot for the Northstar.

And Mike, it's unrelated to your DTCs, but check your fuel pressure regulator. A leaky FPR will cause all sorts of hell with hot starts, and aid cold starts. The FPR is on the fuel rail, just remove the beauty cover on the engine. With the key ON, engine not running, pull the little vacuum hose and check for leaking fuel. Replace the FPR if it leaks. 50 bucks at RockAuto, and about 10 minutes to replace.

whoaru99
09-06-2010, 09:34 AM
I'm sure they're completely different parts, but my 94 Buick acted similarly when the crank position sensor went bad. The Buick had only one sensor though so after a while when it got hot you walked, or waited for it to cool down so it would restart.

M Jarve
09-06-2010, 11:24 AM
I'll take a look at the sensor. I had one go bad on my old Bonneville (98 SSEi), and it was a real PITA to change- had to practically remove the engine to get at the sensor, as it was under/behind/within the harmonic balancer. This sound much easier to get to.

Thanks, and I'll report the results, when I get a chance to look at it.