No scan tool communication
I’m at a loss on finding some info on how Pre-CAN OBD2 Nissan communication line activity should look.
The vehicle in question does run, not well. tried using the ALLDATA, OTC, & Autel scanners, no Bueno. Has 9.2V no matter what on DLC pin 4 SCIRX data line even with all other modules unplugged. DLC pin 5 SCITX has 0 activity.
It’s obvious we have a short to power somewhere, but it would be nice to know what how the system functions.
If the concern is only a running rough engine and you want to check out some PIDs, why not just run a bypass on the network to the ECM? After the tech figures out the main concern then he/she can tackle the no comm. (If customer permits)
If you want to attack the no comm, I would section out the network, separating connectors to narrow down where the network is active and where it isnt.
Your diagram is incorrect. Go look at the full diagram in Alldata and it is correct. Pin 16 is battery voltage, 4&5 are ground. 7 is Kline (generic) and 12/13 are the enhanced side. If you have voltage on 4 and 5, it is a ground issue. Otherwise, have you tried both generic and enhanced on this vehicle?
For a 2000 Nissan Xterra SE 3.3L? Here's the wonderful ECM diagram from Nissan: diag.net/file/fri13ut34… The DLC diagram is what I initiallydiag.net/file/f2qsryg1k…diag.net/file/f5faip514… posted No luck with Generic either. Probably need to go after the wiring issue and then see where we are at.
Yes. See how the 12 volts is now on the short side of the J1960 connector? That's pin 16. The right lower is 1. Using that, you can line up the pins with the proper wires but do not use the second diagram. I still don't know what you are seeing since you were using an incorrect diagram to describe your pin voltages. Restate what you see based on the proper pin out.
Hi Matt, SCI RX and SCI TX are biased to about 10 Volts with a Scan Tool connected. SCI RX toggles low when the Scan Tool tells the vehicle what it wants, and SCI TX toggles low when it responds. After SCI RX sends a request, it is often held to near ground while the module is talking. Are your measurements with or without a Scan Tool connected?
With tool plugged in and monitored on a BOB. I have a located a known good test subject that will be investigated tonight. I appreciate the help!
You mean how the activity would look on a scope? Cant help there, but (ironically) according to Alldata: Pin 4 is 0-4v Pin 5 is 3-9v both readings are with the engine idling.
Tim is on target with what SCI RX and SCI TX should be doing.. here is what the ECM is looking for running, and with a scan tool connected and disconnected at terminal 69.
I appreciate it!
Hello Matt, The reply from Randy Bernklau is valid. Pins 4 and 5 are ground for an OBDII connector. I think we need to figure out which diagram is wrong. I can't imagine a 2000 model year vehicle not following the normal OBDII pin assignment. Keep us posted. Thanks.
To answer the above questions: -YES! The DLC is not federal compliant! -This is not the first vehicle to slip through the cracks. Last week I had a 2013 Hyundai Genesis Coupe 2.0L with a backwards wired DLC. Pins 3 & 11 are high speed CAN as seen below; diag.net/file/f52em2a2d… -Our measurements wre take frm an inline DLC break out box and scan tool plugged in while engine
Now that I think about it, I remember some scan tools do have difficulty communicating with Nissan's of that era, probably because of this non-standard implementation. Also, I found this in Autoenginuity's user manual, so there are a few vehicles out there, as you mention.
Ah, the Mercury Villager - what a unit!diag.net/file/fl5v36h6m…
So is the lack of communication because of the pin arrangement?
Hi Matt, I believe you need to locate the Nissan specific Diagnostic connector that is mounted onto the interior fuse panel. If you have the Autel unit you should have a connector specific for Nissan. I believe you need to pull the interior fuse cover off and find the connector mounted on the fuse panel. I dont have a picture of one but I do remember a nissan truck like that that would not