2008 Pontiac G6 3.5 NO TACHOMETER P0335 HARD START ROUGH IDLE
2008 Pontiac G6 3.5 Keeps throwing P0335 & tachometer does not work Scanner shows no data at tach also Runs rough like a misfire Hard start New crankshaft sensor Completed diagnostics Green wire has 5v with key on Wiggle tested wiring, no drop in voltage Verified purple wire has ground Verified continuity of all 3 wires from ECM plug pins to crankshaft sensor plug All wires have continuity but none with either other (to rule out no melted or touching wires) Ran a 12v load through all 3 wires no drop in voltage Tried a second crankshaft sensor Left sensor plugged in and ran metal across sensor, still no tachometer activity I’m at a loss?? Verified engine speed wire from ECM to sensor is hood but…. Possibly wire from tachometer to ECM??
Did you hook a scope to the sensor wire and see if the sensor was producing a signal? Did you stick a camera in the sensor hole and see if the reluctor was lined up with the sensor?
I did scope the sensor hole & inspected the reluctor wheel, teeth all look good! Unfortunately I do not have a scope
Hi Zach, A scope camera is different than a oscilloscope (both are typically called ‘scopes’). I recommend you get or borrow an oscilloscope and get a capture of the cam and crank to see if the reluctor is out of position. Generally speaking a tach will still work even if the reluctor has spun out of position and still present. So this favors an electrical issue. This problem is pointing at…
Does your scan tool show RPM in engine data? Have you tested to see if the CKP sensor with a lab scope to see if it is producing the correct signal to the PCM? Here are the conditions for setting this DTC, it is pretty much cut & dried. Conditions for Setting the DTC - The ECM does not detect a signal from the CKP sensor. OR - The ECM detects a CKP signal without a reference pulse…
I remember seeing a bulletin in these about the reluctor wheel coming loose from crank and spinning out of time and will still run on cam signals alone but have all your symptoms.
I scoped the sensor hole, teeth looked good, not sure if it spun tho ?
I have had bad sensor harness connectors cause issues like this. For some reason when you test them they show good. Sometimes you just have to try replacing something. Cars don't always go by the book.
Grew up on Whitney ave. With the knechts. Went to school with Sharon. Say Hi for me. Frank.
Hi Cmore, This is often where the debate which is best comes in. Is it better to back probe at the connector, or pierce the wires with probes. Both have there drawbacks. Back probing can apply additional pressure to a weak connector pin while inserted, wen removed the pin relaxes and the problem continues. This often causes “false positives” when testing. Piercing is often used and reliable…
hi Zach I just had one doing same thing all wires sources was good at crank sensor but when hooked up lab scope signal was bad and not showing at times , it was a new ac delco so when I removed crank sensor to take a look at tone wheel it was good and turning , but I noticed all the rust scale build up on block where crank sensor mounts cleaned block good re mounted and car started and tach was…
Absolutely right. Rust jacking the sensor out of the hole. Even though it's a hall sensor it is very sensitive to air gap. Remove the sensor and clean the mounting surface.
3 issues I recall with these like Malibu as well the main engine ground came loose like 5.3 Chevy or loose cable crimp EZ to check above the transaxle ..Grounds studs on the radiator support and loose UHFB connectors not all locked . Damaged reluctor is weird symptoms every once in a while it will catch run and oddly enough no Tach I had a 08 HHR that needed a crankshaft that what it did …
Signal wire should have voltage that goes from high to low as the crank is turned by hand, KOEO. I know you don't have an O-scope, but the DVOM will at least tell you whether there is anything happening at the sensor. Light Blue/Black wire is the signal that should change. Should have voltage on it when disconnected as well.