Challenging RX8
#1
Challenging RX8
Greetings good people
I recently got RX8 from my wife for my birthday, it was a great supprise for me, but after few days it was even greater supprise when i got to know my RX8, it is a mess...electronic mess to be precisse...
Mazda is grey 2005. 170kw, decat, right hand drive converted to left hand drive. Engine is ok, it runs great, starts hot and cold no problem, but it has Check Engine, ABS, Airbag and TCS lights on, and tachometer and speed droping to 0 and jumps right back from time to time...my goal is to bring this car to its original shine, but i need some help, because no one in my country knows how to solve my problems. .
I recently got RX8 from my wife for my birthday, it was a great supprise for me, but after few days it was even greater supprise when i got to know my RX8, it is a mess...electronic mess to be precisse...
Mazda is grey 2005. 170kw, decat, right hand drive converted to left hand drive. Engine is ok, it runs great, starts hot and cold no problem, but it has Check Engine, ABS, Airbag and TCS lights on, and tachometer and speed droping to 0 and jumps right back from time to time...my goal is to bring this car to its original shine, but i need some help, because no one in my country knows how to solve my problems. .
#2
What am I doing here?
Join Date: Mar 2006
Location: 2017 Miata RF Launch Edition
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You bought a can of worms that somebody else opened.
It sounds like they messed up the electrical wiring in a bad way.
The inconsistent tach/speed are probably due to a loose ground wire OR damaged CAN bus wire.
It sounds like they messed up the electrical wiring in a bad way.
The inconsistent tach/speed are probably due to a loose ground wire OR damaged CAN bus wire.
#3
It was a gift
It was a supprise gift, so i didnt have any part in it.
Today i tried replacing instrument cluster with another from junk yard, but tha problem was the same, then i tryied to pull 2 direct separate CAN wires from ECU to instrument cluster separating the original wiring, but the problem was still there... grounding will be my next step.
And i forgot, DSC OFF switch seems to not working, presing it holding it or so, nothing happens, no DSC OFF light...
Today i tried replacing instrument cluster with another from junk yard, but tha problem was the same, then i tryied to pull 2 direct separate CAN wires from ECU to instrument cluster separating the original wiring, but the problem was still there... grounding will be my next step.
And i forgot, DSC OFF switch seems to not working, presing it holding it or so, nothing happens, no DSC OFF light...
#4
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What is the check engine code?
The gauges dropping to zero sounds like loose battery cables or (less likely) other electrical connection problems.
TCS, ABS and steering lights all come on after you disconnect the battery, so that fits.
The DSC OFF function may not work while TCS is in an error state.
One step at a time, let's get the codes. It starts warm, so that's a good sign..
The gauges dropping to zero sounds like loose battery cables or (less likely) other electrical connection problems.
TCS, ABS and steering lights all come on after you disconnect the battery, so that fits.
The DSC OFF function may not work while TCS is in an error state.
One step at a time, let's get the codes. It starts warm, so that's a good sign..
Last edited by Loki; 03-21-2019 at 03:12 PM.
#6
Steering light is not lit, battery is 2 months old and tight...
tomorow ill go to some guy to check ABS codes. I tryed ECU reset, it was successful but after DSC calibration DSC OFF light went off but other 2 stays ( ABS and TCS)...
tomorow ill go to some guy to check ABS codes. I tryed ECU reset, it was successful but after DSC calibration DSC OFF light went off but other 2 stays ( ABS and TCS)...
#9
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Hmm sounds like a loose electrical connection nevertheless.
With car on and stationary, try to wiggle the wiring harness in various places to see if you can make the gauges drop.
It's also possible they're dropping because the ECU is losing power momentarily, so try around there too.
She bought you an exciting project!
With car on and stationary, try to wiggle the wiring harness in various places to see if you can make the gauges drop.
It's also possible they're dropping because the ECU is losing power momentarily, so try around there too.
She bought you an exciting project!
#10
Codes,codes,codes
Today i went to some guy and checked all codes with Mazda V41.50. Every system (ABS,TCS,EPS,IC,RKE,PCM) has code U1900...
Here are all the codes:
ABS/TCS
U1900
C1155
EPS
U1900
IC
U1900
RKE
U1900
PCM
P0037 (this rx is decat)
U0073
And Torque Pro readed two more
U0100
P0763
After clearing the codes,ABS light went off
U1900 stays for EPS,and after few minutes ABS light come on again which i gues is because of a faulty sensor.
Here are all the codes:
ABS/TCS
U1900
C1155
EPS
U1900
IC
U1900
RKE
U1900
PCM
P0037 (this rx is decat)
U0073
And Torque Pro readed two more
U0100
P0763
After clearing the codes,ABS light went off
U1900 stays for EPS,and after few minutes ABS light come on again which i gues is because of a faulty sensor.
#11
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iTrader: (1)
Today i went to some guy and checked all codes with Mazda V41.50. Every system (ABS,TCS,EPS,IC,RKE,PCM) has code U1900...
Here are all the codes:
ABS/TCS
U1900
C1155
EPS
U1900
IC
U1900
RKE
U1900
PCM
P0037 (this rx is decat)
U0073
And Torque Pro readed two more
U0100
P0763
After clearing the codes,ABS light went off
U1900 stays for EPS,and after few minutes ABS light come on again which i gues is because of a faulty sensor.
Here are all the codes:
ABS/TCS
U1900
C1155
EPS
U1900
IC
U1900
RKE
U1900
PCM
P0037 (this rx is decat)
U0073
And Torque Pro readed two more
U0100
P0763
After clearing the codes,ABS light went off
U1900 stays for EPS,and after few minutes ABS light come on again which i gues is because of a faulty sensor.
P0037 should still not happen, as the O2 sensor should still be installed in the decat pipe.
#12
What am I doing here?
Join Date: Mar 2006
Location: 2017 Miata RF Launch Edition
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U1900 and U0073 are both CAN communication error codes. Either the wire harness or harness connectors are damaged or the modules were swapped at some point and nobody bothered to reprogram the ECU to accept them. If these codes don't come back, then it's probably an old stored code from when the previous owner was screwing around. If they do come back after a while, start checking your wiring harnesses and connectors.
ABS/TCS C1155 is an error for the left front wheel speed sensor failed or disconnected (open circuit).
DTC C1145, C1155, C1165, C1175
P0037 means that the rear O2 sensor is bad, not present, or not connected. The presence of the cat has nothing to do with it. If you want that error to go away, put the rear O2 back in and connect it up.
ABS/TCS C1155 is an error for the left front wheel speed sensor failed or disconnected (open circuit).
DTC C1145, C1155, C1165, C1175
P0037 means that the rear O2 sensor is bad, not present, or not connected. The presence of the cat has nothing to do with it. If you want that error to go away, put the rear O2 back in and connect it up.
#13
Hmmmm...is there any way to find out which module does not belong in this car?
As you metioned before i noticed something strange in wireing harness before, the day i received this car it has error for clutch switch, than i checked under the steering wheel and there was none...so i got that switch from a junk yard put that switch on its place but there were not any connector for it, so than i found electrical schematic of RX8 an traced that switch to the ECU but on that pin on the connector there wasnt any wire (it should be purple). Furder studying the electrical scheme i figured, on the automatic transsmision there is no clutch switch and that pin with puprle wire is blank as mine was. I was confused, never the less i added one new wire from that switch to that blank pin on the ECU and error was gone, and even engine idle was much better. So my conclussion is that in my car is w.harness from automatic t. version...but studing this electrical schematic i canot find any major differencess betwen AT and MT, i mean on major systems like CAN bus or so.
I checked VIN number as you suggested, but i can barelly find anything about this car ..i tryed multiple sites and only two of them showed me, that number is for RX8, 2005, 230 HP and 6 speed MANUAL. Thats all..every other showed error in number...
As the instrument cluster concern, yesterday i cut factory CAN lines from wire harrnes in front of the IC connector and pulled 2 new separate wires directly to ECU, and connected them on pins for CAN bus, everything worked but again problems with tacho and speed are still present. So conclusion was, CAN wiring is good. One more thing is when i read RPMs and speed over OBD2 thera are no interupts like on IC...
As you metioned before i noticed something strange in wireing harness before, the day i received this car it has error for clutch switch, than i checked under the steering wheel and there was none...so i got that switch from a junk yard put that switch on its place but there were not any connector for it, so than i found electrical schematic of RX8 an traced that switch to the ECU but on that pin on the connector there wasnt any wire (it should be purple). Furder studying the electrical scheme i figured, on the automatic transsmision there is no clutch switch and that pin with puprle wire is blank as mine was. I was confused, never the less i added one new wire from that switch to that blank pin on the ECU and error was gone, and even engine idle was much better. So my conclussion is that in my car is w.harness from automatic t. version...but studing this electrical schematic i canot find any major differencess betwen AT and MT, i mean on major systems like CAN bus or so.
I checked VIN number as you suggested, but i can barelly find anything about this car ..i tryed multiple sites and only two of them showed me, that number is for RX8, 2005, 230 HP and 6 speed MANUAL. Thats all..every other showed error in number...
As the instrument cluster concern, yesterday i cut factory CAN lines from wire harrnes in front of the IC connector and pulled 2 new separate wires directly to ECU, and connected them on pins for CAN bus, everything worked but again problems with tacho and speed are still present. So conclusion was, CAN wiring is good. One more thing is when i read RPMs and speed over OBD2 thera are no interupts like on IC...
#14
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Hey that's good troubleshooting!
If you post up the module part numbers here for the ECU and ABS module we can help identify what doesn't belong.
So the VIN is for an RHD manual car, but it has the harness from an automatic car (probably LHD) ?
May want to start shopping for a manual LHD wiring harness..
If you post up the module part numbers here for the ECU and ABS module we can help identify what doesn't belong.
So the VIN is for an RHD manual car, but it has the harness from an automatic car (probably LHD) ?
May want to start shopping for a manual LHD wiring harness..
#15
What am I doing here?
Join Date: Mar 2006
Location: 2017 Miata RF Launch Edition
Posts: 3,606
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I can't tell from your description but make sure that your two new CAN bus wires are twisted together. CAN is a twisted-pair physical topology (like Ethernet) where the wires carry the same but opposite charge from each other. Doing this reduces interference into the signaling and caused by the signaling.
If the two wires of the pair aren't twisted, you may get unpredictable results. The easiest way to get twisted pair is a long Ethernet patch cable. It's nice and stranded so it won't work harden and break just from vibration nearly as easily as solid wire (typically installer wire that comes from a spool or a box).
If the two wires of the pair aren't twisted, you may get unpredictable results. The easiest way to get twisted pair is a long Ethernet patch cable. It's nice and stranded so it won't work harden and break just from vibration nearly as easily as solid wire (typically installer wire that comes from a spool or a box).
#16
Thats correct, i used twisted pair...but test was unsuccess, because problem was still there...
Ok, next thing ill collect all numbers from modules and ill post them here...
The car was deffinitly RHD because there are number of things that pointed on that, for example, right seat is full electric and left is not its manual, safety belt if not plugged in on the right side and no one is in the seat is beeping, even central console is opening from right to left, IC is mirrored from LHD, side mirrors are defferent angle, left side cant adjust so far left (you see half of a car in it) and windshield bottle has only one bolt, there is no hole for other... And i found hidden service book under the seat from the first 3 years of the cars life and it was serviced in England.
Ok, next thing ill collect all numbers from modules and ill post them here...
The car was deffinitly RHD because there are number of things that pointed on that, for example, right seat is full electric and left is not its manual, safety belt if not plugged in on the right side and no one is in the seat is beeping, even central console is opening from right to left, IC is mirrored from LHD, side mirrors are defferent angle, left side cant adjust so far left (you see half of a car in it) and windshield bottle has only one bolt, there is no hole for other... And i found hidden service book under the seat from the first 3 years of the cars life and it was serviced in England.
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