LS3 convertion with rev counter problems
Discussion
Hi all. Has anyone on here had a topcats or personal LS3 convertion and had problems with the rev counter? I am having a problem where the rev counter stops working after anywhere between 10 and 30 mins driving depending on how hot it is? I have been told conflicting answers to what the fault could be. I believe its a heat related problem as it can start working again if you get a good run without stopping or traffic. If it's a faulty crank sensor would I not be getting other running problems?
Many thanks for any help
Many thanks for any help
you can plug into the GM ecu and check the rev reading there if you have access to a reader, if youve the standalone GM ecu setup (which is what i would assume topcoats use) you'll have the obd plug. then you will know if its theGM , but more likely is a bad connection between the loom, dash ecu and pod somewhere.
the GM ecu has a rev signal output which you can wire into the input to the dash ECU. thats how i did mine. never had an issue, and the signal form the GM works fine with the TVR pod
is is all of the dash rev readings you lose, or just the needle. you can get rpm reading digitally also, so need to low if both cease working (signal related) of just one (pod related)
the GM ecu has a rev signal output which you can wire into the input to the dash ECU. thats how i did mine. never had an issue, and the signal form the GM works fine with the TVR pod
is is all of the dash rev readings you lose, or just the needle. you can get rpm reading digitally also, so need to low if both cease working (signal related) of just one (pod related)
Edited by SteveSPG on Sunday 19th October 12:04
Both the digital and analog rev readings drop out at the same time and return at the same time. There is no other problems or loss of display on the dash when it happens only the rev counter. I am not hugely electricly minded so if I get a professional to look I need to give him some idea where to start.
Pull the dash pod. Check the connectors for the pod to pod ecu (that's in the footwell drivers side) there is a 24 pin black plug that has most of the wiring connections in the same area. I don't know how yours has been wired but the obvious okace to connect the Rev counter input to the dash is in there
I have removed the pod and checked the connections. I have also removed the dash ecu and by elimination it's the green plug that supplies sensor readings. Do you have any idea witch one is the tac wire? The Sagaris manual does not tell you as far as I can see it only has the main ecu diagrams. If I can find out what wire it is I can test it to see what side the fault is.
I have traced the tac wire on the dash ecu and there is still a signal being sent after the display has dropped out. I have also removed and turned round the ribbons from the dash ecu to the dash pod and it still does it. I have removed the dash to look for dry solder joints but can't really see any. Any more ideas anyone, starting to loose hope :-(
I have run the engine until hot without the dash in the car so it's cool,connected the dash back up with a fan blowing on it to keep it cool and there is no tac reading!!! I am beginning to think it's not a dash problem as that test eliminates that.i also kept the dash ecu cold to see if that was the problem. I guess now it can only be a tac pick up sensor problem or a problem with the Gm 429 ecu loom interface with the tvr remaining loom.?
UFO MATT said:
I have run the engine until hot without the dash in the car so it's cool,connected the dash back up with a fan blowing on it to keep it cool and there is no tac reading!!! I am beginning to think it's not a dash problem as that test eliminates that.i also kept the dash ecu cold to see if that was the problem. I guess now it can only be a tac pick up sensor problem or a problem with the Gm 429 ecu loom interface with the tvr remaining loom.?
I'm not the expert you need so please don't flame me but the lack of tach reading in the above test might be to do with the dash not initiaising when ignition switched on? I mean, that initial needle sweep must be part of something and then there's that problem with HIDS when abnormal startup current confuses the illumination?? I'm sure you're right in saying it must be beyond the engine ECU because otherwise you'd be in a world of trouble. I was doing some lateral Googling in case it was a GM problem. All I found was one chap had an Audi that dropped its tach reading to 0 because an ABS module was reducing the voltage to the dashboard. Don't suppose 10-15min corresponds to the second engine fan cutting in? Or some other heat related function?
Ok I have had the Gm ecu read with an OBD reader and there are no sensor fault codes. I did a meter reading and there is 5volts coming from the Gm ecu supplying the tach feed. Does anyone know if this needs to be more like 12volts? Did the original speed six tach feed have a higher voltage being an older system?
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