× A place to discuss hardware/software and diagnostic procedures

Diagnostics Scanner

  • randy61
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
14 Aug 2019 23:15 #32826 by randy61
Diagnostics Scanner was created by randy61
What type of scanner is there that does NOT have to be connected to the OBD port connector in order to read sensors, fuel trims and injectors?

Please Log in or Create an account to join the conversation.

  • randy61
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
14 Aug 2019 23:16 #32827 by randy61
Replied by randy61 on topic Diagnostics Scanner

randy61 wrote: What type of scanner is there that does NOT have to be connected to the OBD port connector in order to read sensors, fuel trims and injectors?

Please Log in or Create an account to join the conversation.

  • Noah
  • Noah's Avatar
  • Offline
  • Moderator
  • Moderator
  • Massachusetts, USA
More
15 Aug 2019 06:22 #32832 by Noah
Replied by Noah on topic Diagnostics Scanner
A scanner, by definition must be plugged into an OBD port.
OBD standing for on board diagnostics.
after 1996, US vehicles adhere to OBD2 protocol and have a standardized OBD port.
Older vehicles have non standardized ports for factory level scan tools.

So every scanner needs to be plugged into an OBD port, even if it is not the standard plug that we recognize today.

Many scan tools have adapters to connect to pre OBD2 vehicles (snap on , launch, Bosch), but I have very seldom had the need to use them and any time I have, the data and codes available were severely lacking in providing diagnostic direction.

"Learn, apply, repeat."
The following user(s) said Thank You: randy61

Please Log in or Create an account to join the conversation.

More
15 Aug 2019 07:09 #32833 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic Diagnostics Scanner
Pre OBD2 it was OBD1 and by legal requirement all that was stored was a few very general fault codes that were manuafacturer specific, there was no requirement for live data from sensors

" Welcome to the 21st"


The following user(s) said Thank You: Noah, randy61

Please Log in or Create an account to join the conversation.

  • randy61
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
15 Aug 2019 15:53 #32843 by randy61
Replied by randy61 on topic Diagnostics Scanner
I have a 1990 jeep Cherokee which it is pre obd. No codes or any data storage. So basically I would have to rely on a DMM... correct?

Please Log in or Create an account to join the conversation.

More
15 Aug 2019 16:04 #32844 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic Diagnostics Scanner

" Welcome to the 21st"


The following user(s) said Thank You: randy61

Please Log in or Create an account to join the conversation.

  • randy61
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
16 Aug 2019 13:31 - 16 Aug 2019 13:35 #32860 by randy61
Replied by randy61 on topic Diagnostics Scanner
The 90 Cherokee computer does not store or throw codes. It is not OBD1 or 2.
There are no flash codes either. That only worked with newer Cherokee's after 91.
That is a big misconception going around on the internet that flash codes can be had by turning key on and off for 87-90 Cherokee's.
Last edit: 16 Aug 2019 13:35 by randy61.

Please Log in or Create an account to join the conversation.

  • randy61
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
23 Aug 2019 00:26 #33077 by randy61
Replied by randy61 on topic Diagnostics Scanner
I watched scannerdanner testing an intermittent stall, no start -po320, p1391 cam, crank sensor testing (jeep)

His Veris scope wasn't attached to the obd port.
It was attached to the battery terminals and to the sensor wires for a square wave signal between the cam and crank sensors.

So why is it not possible to run a scope on the 1990 jeep Cherokee?

Please Log in or Create an account to join the conversation.

  • Noah
  • Noah's Avatar
  • Offline
  • Moderator
  • Moderator
  • Massachusetts, USA
More
23 Aug 2019 07:48 #33079 by Noah
Replied by Noah on topic Diagnostics Scanner
It is possible to use a lab scope on your Jeep!
While it just happens to be built into the Verus, it is not typical to have a lab scope and scan tool combo, they are two very different tools.
A scope will not provide you with trouble codes or data pids. It is essentially a very fast multi meter that you can use to verify circuit integrity and sensor signals. However, without a frame of reference, the most you can do is verify that a sensor is doing "something".
Luckily for you, you have material to reference!
If you have a scope, the tests that Paul demonstrates on his Jeep should be valid for yours.

"Learn, apply, repeat."
The following user(s) said Thank You: randy61

Please Log in or Create an account to join the conversation.

  • randy61
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
23 Aug 2019 09:47 #33081 by randy61
Replied by randy61 on topic Diagnostics Scanner

Noah wrote: However, without a frame of reference, the most you can do is verify that a sensor is doing "something".
Luckily for you, you have material to reference!


Can you elaborate further regarding?
(without a frame of reference),
(you have material to reference!)

Please Log in or Create an account to join the conversation.

  • Noah
  • Noah's Avatar
  • Offline
  • Moderator
  • Moderator
  • Massachusetts, USA
More
23 Aug 2019 17:52 #33088 by Noah
Replied by Noah on topic Diagnostics Scanner

randy61 wrote:

Noah wrote: However, without a frame of reference, the most you can do is verify that a sensor is doing "something".
Luckily for you, you have material to reference!


Can you elaborate further regarding?
(without a frame of reference),
(you have material to reference!)


What I meant was that if you wanted to perform the same test as in the video, you know what results to expect having seen the tests performed already.

Where as if you suspected say a coolant temperature sensor issue for example, you couldn't just back probe the sensor with a scope and say it's X degrees. Instead you would need to know what voltage correlates to what temperature and determine if it's reporting a reasonable value.
If you had access to scan data, you could scroll through the data pids and see exactly what temperature the computer is inferring from the sensor signal.

Just like your cam and crank signals. On OBD 2 Chrysler vehicles (Jeep included), there's data pids that indicate the presence of cam and crank signals and if they're in sync.
With a scope you would need to capture the signal waveforms, verify that they are within specific voltage range and compare to a known good vehicle to know if there was a synchronisation issue.
Hope that makes sense :)

"Learn, apply, repeat."
The following user(s) said Thank You: randy61

Please Log in or Create an account to join the conversation.

  • Not Allowed: to create new topic.
  • Not Allowed: to reply.
  • Not Allowed: to add attachements.
  • Not Allowed: to edit your message.
Time to create page: 0.634 seconds