New member 2007 Liberty troubleshooting help.

[asw120]

Battery is 1 year old. Was a bit low when I got it; 12.1v. After charging overnight and leaving a while; 12.8v. Not wonderful, but should do the job. Goes straight up to 14.5v on startup. Now the shorted air pump is disconnected, this might help a bit. My daughter has been ignoring the horrible noises under the bonnet hoping they would go away.......
Been out on calls all day at Toowoomba, just got home.
Going to bell the wiring, now as per DTC instructions. Also hoping to check voltages on related ECU pins. I can not understand why that's not referred to in the diagnostic instructions.

Thanks, Jarrod.

[bigBADbenny]

Here’s a link to the FSM multimeter tests, continuity, resistance and voltage drop.
If you’re unfamiliar with these try searching YouTube with eg “the trainer resistance test” and so on.

https://www.dropbox.com/sh/6w38xtm9lv5y ... vPTBa?dl=0

Most of these harness checks refer to a single wires pins, plug to plug, with the harness disconnected from the eg ecu and component, this usually requires an added jumper wire to complete the circuit with the multimeter inline. Of course you can check for continuity between plug pins or ground to find short circuits from worn insulation.

Where relevant testing the component and or the ecu will be covered in the diagnostics.

P0122 P0607 P2109 P2127, P2135 all refer to the accelerator pedal/throttlebody, either component can fail, or the harnesses between the component, ecu and ground.

I’d approach the diagnostics in numerical order since there’s definite taxonomic intent behind the codes, thus the cascading order: fails startup self test, potential failed components or connections.

Try hooking up the secondary air gear as per stock, reset the ecu then read your codes on the odometer again.
I’d be extremely dubious about taking action on a DTC from a third party non SSM obdii reader, especially for a code not listed in your year model FSM. It could be a false indication. The odometer DTC check gets to all factory codes including the canbus and more.

Alternatively if a related code is present, your choices are to replace the faulty components (used parts being financially viable) or since your Postfl ecu is aftermarket tuneable, get the DTC’s disabled and in the case of a stuck open valve, place a welch plug in the air pipe or use a blanking plate to seal the air pipe from exhaust gas.

There’s also the chance that DTC was thrown from a low battery condition.


Here’s a link to your Postfl 2.5i DTC diagnostic screenshots, work in progress.
https://www.dropbox.com/sh/9ly1xwyv3t8d ... eyYma?dl=0

[asw120]

What little time I got at home last weekend, I tried testing for the secondary air valve. Reading the code thoroughly, it says "switching circuit open" and indeed it was. This after I pulled the valve and it sure is stuck open.
I put a tone generator on the ecu pin and followed it up the floor under the dash and pulled out a delete box! This car has now officially gone off script.
I put all that stuff back together and made sure it would start. By this time it was dark. I would like to delete that system properly, but don't know if it would remain legally roadworthy.
I intend to get someone out with a proper scan tool and get live data out of it, but will continue with the DTC tests until then. Two of the wires in P0122 tests are well less than 1megohm above earth and the manual says to replace the ECU for the last one (plugged in test). I will get professional advice before doing that and probably wouldn't do it myself.
I have yet to test ECU to pedal sensor and inspect the throttle body. Just not getting enough time. At least I'm not on call this weekend, but it would be nice to get home before dark.

Jarrod.

[bigBADbenny]

Egr deletes are illegal but you can pass RWC afaik in Australia with one.

I’ve heard of those delete boxes but compared to a blank plate and tune tweak they’re expensive.

Blows my mind how a generic (?) obdii scanner picked up that USDM DTC, certainly one for the books.

If there’s no blank plate, the open valve *can* cause unmetered air to the maf sensor, affecting fuel trim and consequently fuel mileage etc, where a metal egr pipe leads from the exhaust port to the intake manifold, or the fire danger aspect for air pump equipped cars: I’ll check OpposedForces site to be sure of which.

The fault is an example used in this article:
https://www.vehicleservicepros.com/serv ... tured-data

What’s your tone generator tool?
Sounds like a cool toy, pun intended…

SSM scan tool:
$15 vagcom kkl 409.1 and freessm or romraider on pc, btssm on android with female usb a otg adapter to suit your phone.
Generic obdii:
$5 elm327 bt plug, torque app on android.
Obd2australia site $40 bt plug and app for iOS or android.

[bigBADbenny]

Whoops, apologies, your car, if it’s a 2.5i is of course an H4SO… My bad.
Please refer to the relevant diagnostic pages, 2.5i is a single overhead cam, 2.0r is dual…

[Ric]

What’s your tone generator tool?
Sounds like a cool toy, pun intended…

I would assume it's something like this:
https://www.jaycar.com.au/network-cable-tracer/p/XC5090
https://www.radioparts.com.au/product/4 ... ester-blue

I have a few of them.
(Plus one of these beauties, which can locate a break in a long cable to within a metre or two... https://www.radioparts.com.au/product/4 ... port-flash
They can test any cable with one or more conductors, not just CAT5/6 cable.)

[bigBADbenny]

Cheers ric! Might have to invest :drool:

[asw120]

Hi guys, I corrected myself in an earlier post that it's a 2 litre. The DOHC schematics match perfectly.

The tone generator is just an ebay cheapie, but does the job. I also have one of those professional box types, which a retired Telecom linesman gave me. I have never tried to use it.

I have been fixing the back shed and have the car inside, now. Infinitely better.
I did a bit of testing on the accelerator pedal tonight, at the ECU pins. The secondary 5v is fine and it's corresponding 0v measures close enough to 0 ohms to earth. The primary 5v goes down to 1.7v with the pedal plugged in! Also, the 0v is about 40 ohms to earth. Even with this pedal track being about 1.7Kohms, vs about 2.6Kohms on the secondary, I don't think the 5v should load up like that. Next check is the earth pins on the "other side" of the ECU on the same diagram. I wouldn't think a bad earth would cause the 5v to change, but who knows what it's referenced to....
I did also check that there's no unwanted earth on the pedal resistor. Would love to find specs on it.
A couple of the earth checks in the P0122 code were not great, either. Supposed to be over 1 Meg to earth, but only about 2K when tested after plugging in. Says replace ECU. Still have to do those checks at the ECU pins for the pedal codes. I shudder to think what an exchange ECU would cost. I would probably get someone else to fit that, if there is any programming to do.
I'm hoping to find a bad earth tomorrow Also have to check voltages to TPS.
Those tools mentioned above, I saw these online and thought they might be too cheap to be any good. Glad to know they are viable. Do those apps mentioned show all the inputs and outputs, like a more expensive "proper" scan tool?
Appreciate the help, Jarrod.

[bigBADbenny]

The tools I mentioned are for reading codes, logging ecu parameters, etc.
A replacement ecu isn’t that expensive but factor in a complete security handshake set to match from a DOHC 2.0r wreck, or dealership tool level ecu coding, by a dealership or tuner.
For diagnostics a multimeter should suffice.
Whats your location?

[asw120]

Ipswich, Qld.

Jarrod.

[bigBADbenny]

Can we approach the diagnostics in logical order?

IMG_8731.png (234.3 KiB) Viewed 989 times

For test 1, ecu harness plug to any chassis ground, which pins are less than 1 *million ohms* (redact/revised) at the chassis etc?

IMG_8733.png (234.32 KiB) Viewed 989 times

This is the fsm short circuit tests, the second test might be easier since it just uses a multimeter…

[Ric]

1 *milliohm* ??
You're approaching super conductor conditions there.
Even a short circuit may measure up to an ohm, depending upon the wiring.

[asw120]

OK, result.
I approached the faultfinding the way I do at work; look for voltages and then find out why they're not there. The way the book says to do it does my head in; I need to know WHY I'm testing that.
I should correct what I wrote the other night; it was the primary, not the secondary channel that was faulty.
I tested again yesterday morning and also the earth pins. All the earths were good. I found that I had a low resistance to earth on pin B25 with the ECU unplugged (this was tested earlier under P0122, but it just says to fix the short in the wiring - there is no short in the wiring. I possibly had the main secondary air valve in bits at that time). Looking at the wiring diagrams, I saw that B25 feeds the world. I already had the throttle body unplugged, the next and easiest was the main secondary air valve. Bingo, sensor faulty (this is the valve that was stuck open). Plugged everything else back in, checked for 5v: present, cleared the errors and re-read to find only P0413. I suspect the delete box has died, or whatever. (P0413 appears to measure the circuit to the secondary air control relay coil). A tradesman car mechanic / auto elec who does this for a living probably would have started unplugging things straight up after seeing the 5v low.
Started up and now have a driveable car.
Still plenty of things to fix, as my daughter has been ignoring the service reports and a number of faults have accumulated. She is giving it to my son for his first car.
Apparently this delete box came with bungs to go inside the secondary air piping, so that side of things should be OK.

Thanks for all the assistance, Jarrod.

[bigBADbenny]

1 *milliohm* ??
You're approaching super conductor conditions there.
Even a short circuit may measure up to an ohm, depending upon the wiring.

Busted! I’m not immune from ineptitude redact forthcoming…

IMG_9750.png (176.66 KiB) Viewed 957 times

Ugh, that’s a million ohms

Looking at the wiring diagrams, I saw that B25 feeds the world. I already had the throttle body unplugged, the next and easiest was the main secondary air valve. Bingo, sensor faulty (this is the valve that was stuck open). Plugged everything else back in, checked for 5v: present, cleared the errors and re-read to find only P0413. I suspect the delete box has died, or whatever.

Love it, you’re saying the fault with the secondary air valve being stuck open was “stealing” power from the throttlebody?

It’s great to witness your approach to the tests: cheers for the updates & explainers.
I need some help with a similar issue so I might have to send you a pm regarding.

[asw120]

Not exactly, it would appear that the valve has been stuck open for a long time. I noted water / condensation in the plug when I first looked at it and a bit of corrosion, like on a water damaged circuit board. I would say this has got into the sensor and partially shorted it to earth, just not a dead short. So enough to overload the 5v supply, but not enough of a short to blow anything.
The main takeaway from this was not to start until I have the correct matching wiring diagrams. That would have saved a lot of confusion, as not only are the wires different colours, but the pinout for the ECU is almost completely different between engines / markets. This is why nothing made any sense at first. It took multiple visits to get used to how to navigate the manual. It is like no manual I've used previously. At work (lifts and escalators), we know what the inputs and outputs do and what voltage should be present. The issues are usually relay, safety circuit, or position sensor contacts, or such. Testing for open, or shorted wires is the last thing we would ever do as it's a rare occurrence. The last time I had an intermittent short was on a lift that was nearly 60 years old! I did not see in the manual any instruction that suggested unplugging things until the short goes away, even though I would think that would be far more common.
Anyway, feel free to PM me, if you think I may be able to assist. If there is an option to send me an email, do that.

Cheers, Jarrod.