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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » 2012 Grand Cherokee Speed Won't Display

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Author Topic: 2012 Grand Cherokee Speed Won't Display
gyorston
Member
Posts: 10
Post 2012 Grand Cherokee Speed Won
on: August 5, 2020 (GMT)

Hi Community,
I am in Australia and have a 2012 Jeep Grand Cherokee Overland. I am able to connect to the ECU via the Bluetooth OBD2 adapter that I bought. I am able to display live data from many PIDs but for some reason the Speed (OBD) PID does not update live. When i connect and run the Adaptor Status function Speed (OBD) is available.
I created a custom PID using 01 0D and when I test the PID I get a response from the ECU
I connected the adapter and App to my wife’s 2017 Grand Cherokee Overland and it works fine
I connected the adapter and App to my son’s Toyota ute (pickup) and it works fine

Does anyone have any ideas? I would have suspected the DLC but all other PIDs report OK and presumably they are all on the same CANBus.

I appreciate any help that I can get!

As an update to this I ran the custom PID in test mode while driving and the response came back in Hex as an exact match for what the car speedometer was displaying. But when I add the custom PID as a dial I get nothing. My custom PID is:
Mode and PID: 010D
Long Name: VSS 010D
Short name: VSS
Min Value: 0.0
Max Value: 255.0
Scale factor: x1
Unit Type: km/h
Equation: A
OBD Header: 7e0
Diag star:
Diag stop:
Overrides PID:
Remember equation: Store in vehicle profile

Capp777
Member
Posts: 2860
Post Re: 2012 Grand Cherokee Speed Won
on: August 5, 2020 (GMT)

I would try creating a new vehicle profile
with a separate dashboard layout and pids,
to see if your custom pid works in a clean
profile.

gyorston
Member
Posts: 10
Post Re: 2012 Grand Cherokee Speed Won
on: August 6, 2020 (GMT)

Thanks Capp777 – I will give that a try

gyorston
Member
Posts: 10
Post Re: 2012 Grand Cherokee Speed Won
on: August 6, 2020 (GMT)

I had an interesting development. When in test mode I could see the response changing (last 2 digits of response were changing and converting them from hex to decimal=speedo) but the Result of Equation was 0.0. I changed my equation to B (=B) and the Result started moving in line with vehicle speed. When I viewed the PID in a layout it also works now.

It seems odd to me that for some reason the Equation needs to be B. Also of note was that the speed produced by my custom PID was 2km/h slower than on my dashboard – looks like someone has had a go at adjusting the car’s speedo and messed with the ECU in the process.

Anyone heard of this before and how I might fix?
I really wanted the trip PIDS but they all rely on the Speed (OBD)

Capp777
Member
Posts: 2860
Post Re: 2012 Grand Cherokee Speed Won
on: August 6, 2020 (GMT)

I thought it was common practice to
overstate the displayed speed… speeding tickets,
tire wear…

Would you consider posting the raw hex
response your vehicle is reporting?

Will your trip related pids work if you
use your working speed pid to override
the OBD Speed pid?

gyorston
Member
Posts: 10
Post Re: 2012 Grand Cherokee Speed Won
on: August 10, 2020 (GMT)

Quote from Capp777 on August 6, 2020
I thought it was common practice to
overstate the displayed speed… speeding tickets,
tire wear…

Would you consider posting the raw hex
response your vehicle is reporting?

Will your trip related pids work if you
use your working speed pid to override
the OBD Speed pid?

Hi Capp777, the responses i get are interesting. without a header i get 2 lines of responses:
7E804410D0000
7E903410D00

If I add the header 7E0 I only get 1 response:
7E804410D0000

Just looking at this I think the 2nd response is the one I want to read as it only has 1 byte of data.

I did try overriding the OBD Speed PID but the icon went red so I assumed that was bad…. I might try it again…is red bad?

moreause
Member
Posts: 509
Post Re: 2012 Grand Cherokee Speed Won
on: August 10, 2020 (GMT)

yes measured speed and speedo speed is often different

i change a bit depending on legislation
most of the time it’s it cannot indicate lower speed

i have seen +10 km/h on some Volk

cintakc
Member
Posts: 1458
Post Re: 2012 Grand Cherokee Speed Won
on: August 10, 2020 (GMT)

gyorston
to request 010D without Header 7E0, you have response with two ECUs, Engine -7E0/7E8 and AT -7E1/7E9
it would be nice to see the answer to the request 010D in motion, can you have two speed sensors, one gives an answer in the first byte, the other in the second, or you have a two-byte answer

Capp777
Member
Posts: 2860
Post Re: 2012 Grand Cherokee Speed Won
on: August 10, 2020 (GMT)

The two byte answer seems odd to me and
probably why Torque is not reading it correctly.

I would be curious if header 7DF would make
a difference in the response.

gyorston
Member
Posts: 10
Post Re: 2012 Grand Cherokee Speed Won
on: August 10, 2020 (GMT)

Thanks for the responses. I will capture a view of both responses with the car in motion today/tonight and will also try the other header – will report back overnight!

gyorston
Member
Posts: 10
Post Re: 2012 Grand Cherokee Speed Won
on: August 10, 2020 (GMT)

Quote from moreause on August 10, 2020
yes measured speed and speedo speed is often different

i change a bit depending on legislation
most of the time it’s it cannot indicate lower speed

i have seen +10 km/h on some Volk

I agree – the indicated speed is usually 2-3km/hr over actual and this saves us from speeding tickets. Funnily enough my daughter’s VW Golf is the worst I have seen at around 8km/hr over actual

gyorston
Member
Posts: 10
Post Re: 2012 Grand Cherokee Speed Won
on: August 11, 2020 (GMT)

So, I tested the 7DF header and received the same 2 responses as detailed above.

I tried the 7E1 header and it restricted the response to the line with the single byte of data.

I haven’t road tested yet or tested if override works on the trip PIDs

gyorston
Member
Posts: 10
Post Re: 2012 Grand Cherokee Speed Won
on: August 11, 2020 (GMT)

Hi folks,
thanks again for the interest and feedback.

When I ran the PID with no header I received the same 2 responses that changed when the vehicle was moving -they showed the exact result albeit one had 2 bytes of data.

I also assigned my custom PID to override OBD speed and it did get my Trip PIDs working nicely – brilliant result.

I could quite happily proceed with things the way they are but would really like to understand why my ECU is spitting out 2 bytes of 010D instead of 1. I read somewhere that with a Jeep specific OBD App (JScan) you can modify the wheel diameter to adjust speed and this sometimes mucks things up – anyone heard/read that?

I would also like to get the Fuel Level Input working – it says 53% all the time using 012F….

gyorston
Member
Posts: 10
Post Re: 2012 Grand Cherokee Speed Won
on: August 12, 2020 (GMT)

Quote from cintakc on August 10, 2020
gyorston
to request 010D without Header 7E0, you have response with two ECUs, Engine -7E0/7E8 and AT -7E1/7E9
it would be nice to see the answer to the request 010D in motion, can you have two speed sensors, one gives an answer in the first byte, the other in the second, or you have a two-byte answer

Hi cintakc, I didn’t take a snapshot however both responses did return identical results – one in the first byte (only 1 byte available) and one in the second byte (2 bytes available) results matched each other and vehicle speed

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