PC853

Hello all. Been reading many posts on here and have tried a few things in an effort to fix my malibu and diagnose the issue but I officially am stumped.

I have a 2001 v6 Malibu with just a little over 60k miles, we are the second owner. All around it has been in great shape, regularly maintained, and had zero issues or any symptoms leading up. One afternoon we went out to leave and our malibu which we had backed in to our driveway just earlier that morning would refuse to start. I have managed to push it up into my garage and am grateful that it decided to die in the driveway and not somewhere less convenient.

The car cranks but does not fire. the battery was strong, however after me giving it my best after much head scratching, the battery is close to needing to be charged. Key turned to the AC or ON position and on the cluster the only things that illuminate are the odometer and the theft light (which comes on solid and does not flash.) If i attempt to start it, then leave the key in the ON position, the theft light eventually goes out. Once the theft light goes out it still does not start. I have tried all of the "time-out" procedures I could find but this benefits nothing. It does not appear that I am getting any spark while cranking. the fuel rail only periodically seems to get primed (checked by releasing the schrader valve on the passenger side of the block. There is a half tank of fuel in it, although the fuel gauge on the cluster does not "wake up" in any key position. When the key is switched from AC to ON, you can feel a little click coming from the Fuel Pump relay in the fuse box. I have a basic OBD2 code reader but when I hook it up I do not find any codes at all.

I'm stumped. Like I said above, it cranks but does not fire or even stumble. There was no warning or leading symptoms, just got in like usual and tried to start it like usual but it only cranked. What should I do? I really do not want to have to pay to tow it if I can possibly solve this, but not having this car running is costing me money each day.

Thank you in advance to anyone that can help!

EinST

Welcome to the forum. Have you checked the fuses, anything labeled BCM or PCM? Other than that, how familiar are you with electrical troubleshooting (DC voltage, resistance, etc.)? Own a digital multimeter (or analog VOM)?

PC853

Hello EinST.
I have a digital multimeter. Electrical trouble shooting is my achilles heal in automotive maintenance. I am much better with mechanical assemblies, etc., but I am willing to give it an honest effort. I am trying to learn to trouble shoot electrical issues and I think this malibu's problem may be my moment of reckoning.

As far as I can tell through visual inspection, all of the fuses appear to be in working condition (no visually burnt out or broken fuses.) I will need to double check the fuse box lid label, but I do not recall seeing anything labeled BCM (Body Control Module? - I've been reading many alternate threads) or PCM.

I followed one thread through checking for the keyed resistance on the ignition switch, which had a peak value of 6.2k ohms, snipping the yellow signal wire from the switch and soldering a 5.6k ohm resistor bridging to the black wire. on the White wire I had the battery's full charge which at that point was 12v. Doing this tripped the theft light (flashing), and I completed the re-learn procedure, which returned the car to it's prior no-start state (solid theft light, no other gauges turning on, crank but no fire.) I have since removed the resistor and wired the ignition switch back to its original configuration and re-learned it again back to its original state... So I believe the ignition switch to be ruled out as a possible cause for the failure.

PC853

Perhaps I should mention: I scanned the Malibu with an Autel AL-309 OBD2 Scanner, which found no codes...

EinST

Okay, check the voltage level at the PCM ACC fuse in the driver side I/P fuse block with key on. Insert the red probe into the probe hole on the fuse and touch the black probe to something metallic that screws/bolts into the chassis metal. Then, check the voltage level at the Fuel Pump Injectors fuse in the underhood fuse block, again with key on. They both should show battery voltage. We'll go from there.

PC853

Thank you. I will check this tonight and post back first thing in the morning!

PC853

I will borrow a battery charger today and hook the Malibu up. Across the battery I had 10.1v. from the PCM ACC fuse socket to ground with key in "ON" I had 8.25v. Then on the F/P Inj fuse socket to ground with key "ON" I picked up 9v.

EinST

I guess I can't be that lucky since the two values aren't low enough compared to the reference voltage across the battery. Things usually start flaking out below 8V. One thing, the CEL should be on in the I/P cluster with key on, engine off. Thus, either the CEL indicator is burnt out or the PCM isn't powering up. Do the gauges and indicators go through the bulb test okay initially? Also, check the voltage levels at the following (with key on unless always hot):

Ignition System (fuse 41 underhood)
Powertrain Control Module (fuse 44 underhood, always hot)
Powertrain Control Module, Ignition (fuse 39 underhood)
Canister Purge Valve, Powertrain Control Module, Exhaust Gas Recirculation, Heated O2 Sensor (fuse 47 underhood)
IPC/BFC ACC (driver side I/P fuse block)
IPC/HVAC BATT (driver side I/P fuse block, always hot)

PC853

On perhaps 1 of 6 occasions of turning the key past OFF, the indicators flash but for literally only a split second, blink and you miss it. key in any position other than OFF and the only indicators that come on in the cluster are the Theft light (which is steadily illuminated until it times out a few minutes after a crank attempt,) and the odometer/tripometer.

The CEL indicator does not illuminate as far as i have seen in that split second of an occasional blink on the key switch.

I will check these fuse values this evening when i get back home and post back first thing in the morning again.
Thank you.

PC853

So I got the car on the charger last night prior to probing the fuses
The voltage across the battery while on the charger was 12.75

Under the hood, fuse 44, PCM (which should be always hot?) I had ZERO volts - with the key in any position.

IGN SYS (41, key on) 12.36v

PCM, IGN (39, key on) 12.37v

(47, key on) .03v or .04v depending on which side of the fuse i probed(? right side .04, left side .03, is that due to resistance within the fuse itself ?)

F/P INJR (48, key on) 12.37v

Inside the car in the driver's side block,
Fuse (F) BFC BATT (key off) 12.7v, (key acc) a fluctuating reading averaging 12.25v, (key on) 12.5v

(G) PCM ACC (Key off) 0.0v, (key acc) 12.6v, (key on) 12.5v

(J) IPC/BFC ACC (key off) 0.0v, (key acc) 12.6v, (key on) 12.5v

IPC/HVAC BATT (key off) 12.67v, (key acc) 12.63v, (key on) 12.55v


...So does this mean that the PCM is toast? or atleast that is the direction of something that has failed?