Tach and codes

[rjlsho]

Well I just had a tranny put in my 98 STS (runs and drives great), but now the RPM gage doesn't work and it's pulling 2 codes that I didn't have before. The codes are P1350 (ignition control system) and P1375 (IC24X reference circuit high voltage). That does't help me with troubleshooting. Do I need worry? Would either of these have to do with the transmission? What would cause a working tach not work? He checked all the connections and they were fine. Is this controlled by the tranny too? Any help would be appreciated. Thanks, RL

PS. The tranny was from a 97 Deville. He just had to swap the side pan and everything else was fine. Is this the problem?

[rjlsho]

I would still appreciate any input on this if someone else has had this problem and diagnosed it, but I found this doing a google search and thought it might help someone else.

The P1350 deals with the ignition module and the PCM/computer but if a
P1375 sets that code, it is to be diagnosed first. The 2 crankshaft sensors, cam sensor, ignition module, PCM are the main components along with their related wires and connector terminals. The fact that the starter spins over normal but takes a little longer to start and along with the tps voltage needing to be higher might lead to a weak fuel pump or poor pressure. But with the tach inoperable, it would point to the 2 crankshaft sensors as the likely suspects. As you can see there are several things to test and as you probably found out the parts aren't cheap and can't be returned once they have been used. If I was going to replace something it would be both crankshaft sensors. In fact Cadillac had problems around '00 and published a bulletin to replace both when the engine started hard or misfired going down the road. The spec useing a digital ohmeter for the crank sensor is 800-1600ohms. Hope that helps.

[submariner409]

I replied to your other post in here on the same general subject. I believe that your car would set either codes P0335/6 or P0385/6 if the CKP (CranKshaft Position sensor(S)) were at fault. The P1375 is not necessarily the fault of any individual ignition control sensor: rather it is the signal control voltage generated by the PCM or one of its circuits.

The CKP TSB published by Cadillac in 2003 (I think) referred to low-speed or coast-to-idle stalling, with a possible P0300 code set also. I also believe that TSB referred to 2000 and later models, so your other correspondent may have earlier info than I.

As I said in your other thread, there is literally a novel written in CF on CKP's. Read up.