C5 No communication to Hptuners
04-24-2018, 09:56 PM
#3
My first thought is what you already mentioned in your first post. What you should do is pull the codes from the car. The code readers don't show all your codes for the car. The C5 has on board diagnostics on it so you can read all the codes for the car. What you need to do is pull your codes and put the codes up so people can further help you. What I would suspect to see is U codes if these modules are not talking to each other or the OBD2 port. These codes are followed by a C for current code or an H for a history code. Below is a link on how to read the codes on the cars DIC.
04-29-2018, 05:02 PM
#5
Update: checked the voltage for battery vs DIC reads and the battery reads 12.2-12.3 while the DIC reads 11.6-11.9. Is this a ignition switch problem?
also checked the OBD 2 port pin 16 for power and it read 11.8-11.7, but how do i check the other 4 pins? Is it in ohms for resistance or volts for reference?
05-02-2018, 12:40 PM
#6
Pro
Update: checked the voltage for battery vs DIC reads and the battery reads 12.2-12.3 while the DIC reads 11.6-11.9. Is this a ignition switch problem?
also checked the OBD 2 port pin 16 for power and it read 11.8-11.7, but how do i check the other 4 pins? Is it in ohms for resistance or volts for reference?
Last edited by midnight01; 05-02-2018 at 12:41 PM.
05-02-2018, 08:13 PM
#7
I had the same problem, turns out my defogger relay was shorted out as well as the interior relay and it kept blowing the fuse, unplug ththose 2 relays then replace the fuse with a known good one and see if it has power. check the male connectors and make sure none are bent or crooked.
05-03-2018, 01:32 AM
#8
Update: Tried out my buddie's Hptuners and it WORKS!, only thing I've done since the last tune visit is clean the hell out of the battery terminals and replaced the bolts. taking it back to tuner soon!
05-17-2018, 09:51 PM
#9
Ok so...... things are getting pretty dumb. I should of stayed in f-bodies lol. The problem im having now is that the pcm hooks up to hp tuners fine when the vehicle is cold or sat for 2-3 hours, but once the car gets warmed up it loses connection from vcm. I’m out of ideas, the car is driving fine from the bench tune so i can still drive it everyday, but its not ready for wot 😢.
i got a suggestion to check voltage from the volts going to the OBD port and when its warmed up it has 12.5 key in the on position and 12.2-12.3 when the car has sat for 2 hours. That was while using the ground on the pin 4/5 to check.
One thing that happened while i was installing the starter is have the ground wire to the pcm get mixed up and put on the starter solenoid. After putting it back to the block it has been fine.
Im open to any suggestion, thanks everyone!
i got a suggestion to check voltage from the volts going to the OBD port and when its warmed up it has 12.5 key in the on position and 12.2-12.3 when the car has sat for 2 hours. That was while using the ground on the pin 4/5 to check.
One thing that happened while i was installing the starter is have the ground wire to the pcm get mixed up and put on the starter solenoid. After putting it back to the block it has been fine.
Im open to any suggestion, thanks everyone!
05-23-2018, 11:36 PM
#10
Team Owner
I never do a upload of a configuration without a battery charger on the car anymore. I just had too many scares and I bricked One PCM that cost about a thousand bucks to fix all said and done
There is a gizmo you can purchase which will allow you to isolate modules on the serial bus to do diagnostics. It also allows you to isolate the PCM so you are writing to that without all the other connections to the other devices in the car, potentially causing Communications issues.. I don't know the brand of the Gizmo but I do have one here. It's basically a rotary switch and it plugs in to a connector in the passenger footwell which is just a great big in line 8 or 10 pin connector, basically just a jumper. When you plug this device into it you can select what module you want to communicate with and that will be the only device receiving power and Communications from the PCM. If I can remember it I will try to get you some information on it tomorrow.
In the meantime, hook up a battery charger while you're attempting to communicate. It shouldn't be a problem doing a scan but if you're writing a tune up to the car, absolutely hook up a charger so you make certain there's good voltage on the bus.
There is a gizmo you can purchase which will allow you to isolate modules on the serial bus to do diagnostics. It also allows you to isolate the PCM so you are writing to that without all the other connections to the other devices in the car, potentially causing Communications issues.. I don't know the brand of the Gizmo but I do have one here. It's basically a rotary switch and it plugs in to a connector in the passenger footwell which is just a great big in line 8 or 10 pin connector, basically just a jumper. When you plug this device into it you can select what module you want to communicate with and that will be the only device receiving power and Communications from the PCM. If I can remember it I will try to get you some information on it tomorrow.
In the meantime, hook up a battery charger while you're attempting to communicate. It shouldn't be a problem doing a scan but if you're writing a tune up to the car, absolutely hook up a charger so you make certain there's good voltage on the bus.
05-31-2018, 10:31 AM
#11
Melting Slicks
If you battery is only showing 12.2 or so It is time to replace the battery. You can try to charge it, let it sit for 12 hours and retest. If it is less than 12.5V, that is more than likely the problem. It has been reported many times by former GM employees when the battery goes under 12.5V it does funny things to the electronics
