Nasty error codes

[V8 Vum]

Right...with my new friend REV on my iPhone I set to dicover the error codes causing my throttle problem (none!)

Oh heck!

p0641 - Sensor Ref Voltage 'A' Circuit open
p0122 - Throttle Position Sensor Switch 'A' Circuit Low
p0223 - Throttle Position Sensor Switch 'B' Circuit High input

This sounds NASTY

This is the very first time I have attempted to start this engine from Jeff Schwartz

Any help on what to do, would be very much appreciated!

[SchimmS]

V8 Vum said:

Right...with my new friend REV on my iPhone I set to dicover the error codes causing my throttle problem (none!)

Oh heck!

p0641 - Sensor Ref Voltage 'A' Circuit open
p0122 - Throttle Position Sensor Switch 'A' Circuit Low
p0223 - Throttle Position Sensor Switch 'B' Circuit High input

This sounds NASTY

This is the very first time I have attempted to start this engine from Jeff Schwartz

Any help on what to do, would be very much appreciated!

Keith,

I used the same program on basically the same engine from the same supplier and also had the p0122 and p0223 codes. It turned out later that the programming for the throttle pedal was totally useless - you could start by checking the wiring on the TPS and the actual throttle position. Mine was somewhere around 20% in idle (where it should be around 0%) and only 87% at WOT. Had to be reprogrammed, I think I even replaced the pedal in the end.
Check first that the TPS connector is clean and properly mated to the TPS sensor.
The TPS sensor should be supplied with 5V on the A terminal of the connector harness side with ignition ON, engine OFF. The B terminal should be at ground potential.
Now with the engine and ignition OFF, and looking at the sensor itself, the resistance measured between the C and B terminals should be near zero with the throttle closed, and move smoothly up to around 4000- 5000 ohms as the throttle is manually moved from closed to fully open.
It could also mean a broken TPS, you should start checking that first, maybe this info will be of some use:
www.aa1car.com/library/tps_sensors.htm

I`ll try to remember what else we did...

Edited by SchimmS on Tuesday 14th September 20:16

Edited by SchimmS on Tuesday 14th September 20:21

[V8 Vum]

Hey Sven, how you doin'!

Thanks for the advice!

Just before I saw your post I had cleaned the contacts on the TBody plug, disconnected the battery for 5 mins reconnected and cleared the errors and......the TP sensor errors seem to have gone away with the ign on.

But I am still left with the original error 0641 which won't go away...

What do you recon? What does it indicate? What can I try?

BTW this all started because I was getting no throttle response whatsoever. The engine idles...but that is about IT!

cheers

Keith

[738 driver]

......Just on that WOT figure, the LS FBW system does not run at 100% WOT on the stock manifold. From memory peak power is somewhere from 87 to 90 odd% ....def not 100%... Strange but seemingly correct.

[SchimmS]

Hey Keith,

good to hear that you got that sorted so quickly. 738 is right about the WOT issue, so you shouldn`t bother about that too much. The p0641 indicates a problem with the 5-volt reference circuit for the MAP and oil pressure sensors. It can be caused by a defect in the sensors themselves, internally in the PCM, or wiring. So it would be a matter of checking those sensors (and maybe some more) to see if one of them is bad, messing around with that 5 volt signal. Delete the codes after that and / or remove the ECU from the battery for 10 mins.
When the engine runs you might also want to check if it goes into closed loop (which mine didn`t).
Keep us updated on the progress.

[V8 Vum]

Hmmm,

Interesting that you mention oil pressure!

I must admit I was a bit surprised to note that there was NO OIL pressure sensor input to the ecu loom!

There is a port that JS had tapped just above the oil filter housing, but as I said, no corresponding way of connecting up to the ECU. I have now used this port with a SPA oil sensore to separate guage.

Should the ECU loom have had such a connector? I was told by JS that the loom was made up by one of his suppliers.

let me know...

cheers

[V8 Vum]

Thanks for the help so far Guys ! I feel I am getting somewhere!

Any idea where I could get a wiring diag and pin-out ID for the loom/ connectors & ECU? That would help a lot!

Since I first posted I have had a reply from Jeff and he tell me that although the ECU is stamped E98 it is in-fact an E38 if that helps?

cheers

Keith

[UltimaCH]

V8 Vum said:

Thanks for the help so far Guys ! I feel I am getting somewhere!

Any idea where I could get a wiring diag and pin-out ID for the loom/ connectors & ECU? That would help a lot!

Since I first posted I have had a reply from Jeff and he tell me that although the ECU is stamped E98 it is in-fact an E38 if that helps?

cheers

Keith

Hi Keith,
Just my 2p's but have you tried looking and asking around in the LS tech forums?
http://www.ls1tech.com/forums/ls1-ls2-ls3-ls6-ls7-...

[V8 Vum]

V8 Vum said:

I must admit I was a bit surprised to note that there was NO OIL pressure sensor input to the ecu loom!

Did yours have one? ..should there be one?

cheers

[RussF]

V8 Vum said:

Thanks for the help so far Guys ! I feel I am getting somewhere!

Any idea where I could get a wiring diag and pin-out ID for the loom/ connectors & ECU? That would help a lot!

Since I first posted I have had a reply from Jeff and he tell me that although the ECU is stamped E98 it is in-fact an E38 if that helps?

cheers

Keith

Uploaded a couple of bits of info here, may be useful.

HTH

[V8 Vum]

Russ,

That is absolutely brilliant! Everyone should have these that run an LS7 - fantastic!

Will make my diagnosing much more possible!

Think this should be posted as a sticky, however not sure of the source or copyright?

Looks like a lot of bed-time reading!

Notice that the Unit does sense the Oil pressure, yet as I said, I have no lead for this to the ECU, and I am wondering why?


I am going to check the wiring and see if there is a tail somewhere. If not I presume I could add one? The only thng is whether I could/should use the SPA sensor in tandem. Don't even know if the signal is the right type, or even if doubling up this way is an option! Seems mad top have two: one for the dash and one for the ECU!

cheers

[RussF]

Full service manual--> http://www.helminc.com/helm/Result.asp?session=1A2...

[V8 Vum]

Hi Russ,

Interesting... Did you get this yourself?

I notice that when you add to cart...you get a red warning saying "This manual is a digital reprint of the original publication. It is possible that this item will be in loose-leaf format. Any wiring diagrams in the original shop/service manual are NOT reproduceable and are no longer available."

Does this mean someone is photocopying the manula and then making money out of selling the photocopies?

If you did get this, in your opinion is it worth the dosh?

cheers

[RussF]

PM on its way....

[V8 Vum]

Right Guys, and with your useful advice - I have got to the bottom of the problem - but raises another!

Checking the voltage on the ref circuit I found 1.4 volts!
So through a process of elimination I found that no sensors seemed to be the culprit????

Then I hd a flash of inspiration and disconnected the alternator plug...and voila - 5v ref sprang back into life!

...and the engine started and revved!

..So, what the heck is going on with the Alternatorfield duty and turn on circuit?

Any bright ideas?

cheers