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Output using GPS is working fine, since it takes readings from tablet GPS.
But output using ECU gives me 0 reading always. Infact this option is marked green when I choose to add dials!

Though speedometer works fine, but ECU is not reporting speed reading only, other parameters are reported by ECU :confused:.

Siddharth

Attention: For those of you using the OBD readers which are like this:


IMAGE SOURCE: http://www.totalcardiagnostics.com/i...luetooth-2.jpg

I noticed that in my device, there was a possible defect in design. That is, the OBD connector is stuffed into the housing of the reader in such a way that one of the pins of the OBD connector comes in contact with the input of a regulator IC on the board. This will result in pin 7 of your OBD connector shorting with pin 16 which is providing battery voltage, ie 14v. In simple words, pin 7 is used for certain protocols to send and receieve data. So returning 14v through this may not be a good thing for the ECU, though it may have appropriate protection. Perhaps your car may not be using the protocol that makes use of pin 7 and hence the connection is non existent to the ECU. But before you try it on someone elses car that may use pin 7, make sure that the following defect is not there. Else, showing off the cool features of ELM and torque to your relative/friend may cost their ECU :D

Here is how the whole thing looks when its housing is removed:


With the connector removed, note the highlighted IC:



Take a second look:



Now when the connector and board are put back in the housing, here is how the highlighted IC sits:



You can notice that the connector pins are coming in contact with the IC



The highlighted portion will show how the short happens

To avoid any issues, here is a stopgap arrangement. Will shortly add rubber sleeves to each pin to make it cleaner, as of now my heat gun is screwed:



Hence, if you have this contraption, look into the circuit and ensure that the OBD connector is insulated from the board. Sending a 14v voltage back to an input of an ECU may not be good. Else you might end up in trouble. Maybe I guess thats why I was getting a wrong battery voltage reading of 5v, which is the output of the regulator IC.

Guys,

Any idea what fault causes a P1120 diagnostic trouble code on a NA Tata Indica diesel, with a Delphi ECU?

This is the DTC I get with my Autel OBD code reader when I hooked it up to the Indica cab that my dad uses to travel to/from work. The check engine light comes on intermittently, and when it is on, the driver says the engine idles in a rough manner, loses power during acceleration and noise is also higher. I sat in it for a brief while during idling, and the noise is indeed higher and the idle is erratic and rough as well.

My code reader says it is a manufacturer (Tata) specific error code. I couldn't find any Tata specific error code guide online, and a P1120 code with most other manufacturers is an issue with the throttle position sensor circuit. However, the NA diesel does not have a throttle position sensor, as it has a mechanical throttle. So it must be something different, specific to Tata.

What could be the cause of this issue?

Thanks in advance!

Scary!
Any such defect with the mini obd dongle like this one?

:eek::confused: What makes you say that?

Since the device doesnt have any wires like the one I have, I dont think there is a need to worry. Will dissect one of them and check.

I guess it's the inexperience and lack of knowledge/expertise of a novice like me. stupid:

I thought the Indica's 475DL NA, being an old school IDI engine, would not have something like a TPS, as it's not a drive-by-wire system controlled by the ECU. I guess I'm wrong and confused a TPS with something else.

In fact, judging by your reaction, DerAlte, I'm sure I got it wrong and was way off the mark on this one. :eek:

So the Indica 475DL NA does have a throttle position sensor then. Is a TPS a basic and standard feature even on old technology engines, or did Tata include the TPS in order to make the aging engine meet BSIII emission norms? The cab whose engine we're talking about is an early 2012 model.

What do you think, DerAlte? You're the knowledgeable and experienced guru here. Is the P1120 DTC on the 475DL NA caused by a faulty/malfunctioning throttle position sensor then, as P1120 means a TPS fault for most makes (I could not get any online material about Tata, though). Or could there be some other possible reason for this?

Your reply would be greatly appreciated and useful. Thank you!

A 2012 Indica is ultra-modern, baba (with some riders, of course :)). Nothing to do with the fact that it has an IDI engine. IDI is only to get lesser vibrations (DI is notoriously noisy comparatively), as this is primarily a car and not a truck.

Most likely the TPS connection to the ECU is loose, i.e. the connector connected to the potentiometer at the top of the Acc pedal is having intermittence. Every time there is a short disconnection, the ECU thinks the TPS (it is just a potentionmeter) is faulty, it tries to go into 'Limp Home' mode, in which speed is restricted to 50Kmph or so. This corrects itself whenever the connection becomes OK. The driver sees this as jerking or loss of power.

The workshop guys only need to remove it and fit it again after cleaning it.

Hehehe. Tata are indeed capable of using the latest technologies in their vehicles, but somehow are still (to this day) flogging the poor 475DL NA on the Indica. I can understand why, though. The cabbies love a simple, cost effective and easily repairable engine without too many expensive-to-fix components, and it fits the bill.

Tata have been forced to include an ECU and some other modern technological stuff on the 475DL NA to meet the BSIII emission norms, the maximum it's capable of. I remember that the Y2K model Indica DLE (pre-V2) we had earlier didn't have an ECU, and was just a couple of steps up on the evolutionary ladder compared to an Ambassador's 1489cc BMC-derived diesel lump. :)

Ah, so this thing that's responsible for the error code is near the accelerator pedal in the cabin, then. Let me see if I can locate this little gizmo and point it out to the driver when the cab comes tomorrow.

I pass on this information to the cab driver. He'll be quite relieved to hear it's something relatively simple, quick and inexpensive to fix.

You've been very helpful, DerAlte! Thank you so much, guru, I really appreciate it! clap:

Do Volvo buses like B7R and Tata Trucks have an OBD 2 Port?

Volvo will definitely have one since its too complex to not have one :D But yes since the bus has quite a lot of electronics involved they will have a diagnostic port, not sure whether they follow the same protocol as cars. Think they have a separate protocol either for manufacturer or generally for heavy vehicles.

The latest buses from both AL and TATA, mostly the common rail engines or BS4 engines are required to come with a diagnostic port at least for the city bus versions. I read this in a document by JNNURM which had the requisites for al categories of bus that could be purchased for the city transport corporations or any govt transport organisation under the scheme. Will share the exact details if required.

Found this little matter while surfing for the answer to your question and AFAIK, Volvo trucks use an 8-pin connector.

Source: http://www.fadaindia.org/news-basket...e-country.html

Anurag.

I use this device, and it also tells me the error. Code. But... Big problem. Most error codes used are manufacturer specific. And its impossible to find out what do they mean unless you have an internationally popular car like a VW etc.,
For example. P1253, P0000

It would be great to get hands on manufacturer specific manuals.

P0000 is a generic code, P1253 is a manufacturer specific code.

Just about everything is freely available on the internet. Just google for your code mentioned make and model will very often get you good results.

Here's an informative forum: http://www.obd-codes.com/trouble_codes/volkswagen/

These days most manufactures don't produce paper workshopmanuals. It all digital. The good news is that it tends to get copied and made available to the public at large. Lots of companies around that will provide a full digital copy of the manufacturers workshop manuals, including OBD / DTC codes and trouble shoot guidelines, diagrams etc.

Again, google around, you might find them on Ebay as well. Not sure how big manufacturers like for instance Mercedes or BMW handle this. Sometimes they have country specific manuals. E.g. Jaguar has some specific American manuals. Having said that, in most case the actual difference are very small between the same model in different countries.

have a look at this website: http://www.alldatadiy.com/

When I lived in the states I took a subscription with these guys for the various cars and models I owned at that time. All manuals, electical, OBD, maintenance information everything is available, including the various Technical Bulletin that manufacturers produce.

Jeroen

Thanks Jeroen. I am aware of this. the problem is that if I have a honda/VW/Toyota, there are no issues. But finding something for Tata is impossible!