Conclusion: crank position sensor intermittent failure during below-freezing temperatures. New sensor fixed it.

Here's a strange one...my '07 Limited with V6 at 248K miles has now died on me twice shortly after coming to a stop. First time was back in November, it started right back up and no further issue until yesterday, when it happened again and took a few tries before it restarted. Both times there was no rough idle or misfire, engine just shut off.

Scantool showed a historical P0230 Fuel Pump Primary Circuit error code stored. Fuel trims are normal at idle while running, showing +0.78% on both banks.

Shop manual section on P0230 focuses on the Fuel Pump Relay and the ECM relay pull pin. However, it also states:

"During idling or under light loads, Tr2 goes ON, and then power is supplied to the fuel pump via the fuel pump resistor. The fuel pump operates at low speed."

Given the problem only happens at idle, I'm narrowing the troubleshoot down to the Fuel Pump Relay (pin 5 connects to the Fuel Pump Resistor) and the Fuel Pump Resistor.

I removed the FP Relay and found a bit of black grime on one of the pins, cleaned the relay and fuse panel pins with DeOxit spray, then swapped that relay for the identical ACC CUT relay. No further issue yesterday while running errands, but the problem has been very sporadic.

Next move is to disconnect the big FP Resistor, measure resistance vs. spec, inspect the pins, and apply DeOxit spray as a preventive measure.

According to the schematic here are two other relays involved supplying fuel pump power: CKT OPEN relay, and EFI relay. Also the main EFI fuse. Unlikely these are a problem as they would take out the fuel pump under all operating conditions, but I'll remove/inspect/clean them for good measure. More to come if it happens again.

your fuel pump could be starting to fail.

At 247K miles it's had a good life. However, it's an unusual failure mode in my experience. Usually I've seen dying in-tank pumps misbehave on initial startup, and long term fuel trims climb into the higher percentages. On the other hand...those were vehicles that didn't have low-speed operation at idle.

If the problem happens again after ruling out the relay(s) and FP resistor, I'll plan on dropping the tank and replacing the fuel pump with a Toyota part. Did this on my previous '03 Tundra as preventive maintenance without much profanity.

edit: the P0230 error code is not related to the fuel pump, only the control circuit. ECM monitors the fuel pump relay pull circuit, it can't monitor the fuel pump itself.

How to Fix a Car that Randomly Dies while Driving
YouTube · 2,050,000+ views · 9/10/2013 · by Scotty Kilmer

scotty kilmer engine shuts off - Bing video



scotty kilmer engine shuts off - Bing video

Update: it happened again today, no error code stored this time. Same pattern as the two priors...cold weather, first stop after sitting for >30sec at a red light the engine just stalled. It fired right back up after switching the key to OFF, then re-starting.

Long Term Fuel Trims at idle are -3.91% bank 1, -3.13% bank 2. Operating range during the drive home shows max of +3.13 on both banks...fuel pump is keeping up with demand no problem.

Prior to this I had cleaned terminals and swapped the Fuel Pump Relay, and replaced the Fuel Pump Resistor with a used piece after verifying resistance met spec printed on the case.

This only happens when the ECU spins down the pump at idle as described in the shop manual: signaling via the Tr2 pin on the ECU and supplying reduced power to the fuel pump via the Fuel Pump Resistor.

This leaves the following as possible causes according to the shop manual diagram:

CKT OPEN relay
EFI relay
EFI fuse
Tr2 pin on the ECU
Tr2 driver
fuel pump

This evening I'll remove, inspect, and DeOxit spray the pins on the CKT OPEN and EFI relays, and EFI fuse.

Then I'll access the ECU with the battery ground disconnected and disconnect/inspect/reconnect the ECU connector with the Tr2 pin.

If it happens again after that, it's down the the ECU Tr2 driver itself and the fuel pump. I have a junkyard ECU here, just need to program the VIN.

And then it's the fuel pump. No other signs of failure here, but that is during full-voltage operation (startup, warmup, driving). If it's having issues spinning at reduced voltage (idling at operating temp) that is good reason to replace after all the above possible causes are ruled out.

Edit: just pulled CKT OPEN and EFI relays, no issues with pins. EFI 30a fuse had issues as shown in pic, replaced.

More to come...

Attached Images

 

Update: today it shut down while moving, this time it showed P0335 Crank Position Sensor A Circuit error code. Coasted to a stop on the shoulder, it started right back up and ran fine the rest of the short trip. Not fun.

Only discernible pattern is cold weather, and vehicle not fully warmed up. This shutdown while moving, and the P0335, are new variables.

It's looking like an ECM issue given the different error codes with no other commonality.

I have a spare ECM and a shop tool to write the VIN after doing the 30min immobilizer handshake. More to come.

Update: I swapped the ECM and did the Immobilizer handshake for 30mins, shop scanner battery was dead so no VIN rewrite yet while it charges.

Engine shut down during the test drive (19degF ambient temp) after I came to a stop still in Drive. No error code. Interesting variation: after the restart and sitting in Neutral for about a minute connecting the little scanner, the engine stumbled momentarily but recovered to normal smooth idle. No further issue for the rest of the ~3 mile test drive, normal LTFT values.

Looking like the fuel pump is going out, the stall only happens when the ECM pulls Tr2 and supplies reduced voltage to the fuel pump and the fuel pump is below freezing temp.

No fuel pressure test kits available locally, AutoZone loaner is on the way arriving next week. Debating a visit to the dealer just to get it over with, as there's no way I'm doing a fuel pump swap in this cold even in the garage.

I took it for two drives this morning in 11degF temp, no stalling. Tried to induce it with prolonged ~3 minute idling in gear, normal driving on same route where it's stalled twice previously.

Plan is to leave the replacement ECM in, test fuel pressure when the kit arrives next week, and go from there. Assuming the kit adapter has a schraeder valve, I have a fuel pressure gauge with a long tube that can run out the hood and tape to the windshield for observation while driving uphill under load to check for pressure drop.

More to come...

If you wind up having to swap the fuel pump, you can just take a dremel tool and make the hole for the electrical plug bigger, then you can remove the pump without dropping the tank or paying a stealership. Food for thought.

It's a PITA but I don't mind dropping the tank when the temps are warmer. No offense and I appreciate the advice, but I don't cut sheetmetal. Sure would have been nice if Toyota had made that access panel hole a bit bigger.

Update: the fuel pump test kit arrived today, hooked it up and found 43psi steady at operating temp and held ~26psi after shutdown for 2 minutes. Shop manual said 5 minutes but at 2 it wasn't dropping any further. I don't have long cranking to start, so post-shutdown pressure holding isn't an immediate concern.

I'll run another test in the morning cold since that's where my problem was/is.

I'm noticing what may be the same problem, albeit while driving with gas pedal applied. First few times it felt like a bump in the road so I disregarded it, today it was clearly an engine hiccup as I was on a smooth surface.

Seems like a momentary loss of power which recovers immediately, causing a shock to the drivetrain. No error code. It happens under the same conditions as the previous stalls:

Below freezing ambient temp;
First drive after cold startup;
Symptom onsets ~5 minutes after start;
No further issue for remainder of drive or subsequent restarts.

This change in symptoms happened after my Jan 27th post where I pulled the CKT OPEN relay and EFI relay. I also replaced the ECM later that day, and it stalled while idling as posted previously. I wrote that off to fuel trim learning, as it hasn't stalled while idling since then...but now I'm tracking this hiccup that happens while driving.

Next up: cold fuel pressure test, and grabbing replacement relays for CKT OPEN, EFI, and Fuel Pump after a thorough study of the wiring diagram.

Update: cold fuel pressure test showed 43.x psi steady, 26degF ambient temp. Fuel pump is ruled out as cause of problem.

Given the change in problem symptoms (stalling at idle changed to momentary loss of power while moving) followed the rearrangement of the EFI and CKT OPEN relays, I'm focusing there.

I have 3 new relays on order at the dealer, these will replace:

• CKT OPEN relay: supplies power to EFI relay;
• EFI relay: supplies power to Fuel Pump Relay and two ECM 12VDC feeds;
• (spare, there are 6 of this relay part# on the panel)

At this point I'm not convinced that the ECM replacement was necessary, but it's done and programmed w/ my VIN so it stays in.

More to come.

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What was happening when my pump went bad, it would hold minimum pressure running for about 30 minutes driving around, but the trim would go up as the pump warmed up and got weaker, indicating a drop in pressure, which was confirmed when I would return to the garage and plug back in.
The current symptom you describe, the momentary loss of power while moving, almost sounds like a fault in the throttle position or pedal position sensors

Solid observations on your fuel trims, mine are consistently < 4% including acceleration uphill.

TPS and pedal connectors added to the troubleshooting list if the problem continues after relay replacements, I appreciate the ideas! Good opportunity to clean & treat the pins while they're open.

Update: it's the crank position sensor. Engine stalled this morning at 29degF ambient, same conditions as previous...first drive after cold startup. P0335 error code set in Confirmed, Pending, and Historical status.

That P0230 that I saw after stall #2 was in Historical status only at that time and may not have been related to the stall. Have not seen P0230 again during all this troubleshoot and scanning.

Fun times ahead pulling the AC compressor and serp belt tensioner to access it. Will check for signs of wiring harness damage, rodent chewing or whatnot.