I was recently asked to look at a Hyundai santa fe displaying an abs fault, the customer reported abs +esp warning lamps on with pre-heat lamp flashing also. Upon reading the error codes in abs and engine management modules one code was retrieved from each, abs module displayed C1702 (variant coding error)and engine management P1593 (four wheel drive recognition)
It appeared that the two modules concerned were unable to establish variant of vehicle i.e. two wheel drive or four wheel drive upon initialisation, in the case of the pcm this is achieved by the grounding of pin 65 on the module and communication with the transfer case module.
I had noticed earlier that the differential lock warning lamp was inoperative so the next step was to check for any faults associated with the transfer case module (four wheel drive module). At this point i discovered the G scan could not establish communications with the module.
It was now evident that this could be the problem and that the pcm and abs modules could not see the transfer case module in the can bus line. I then located the module (passenger footwell) and began to check the pin values, pins 13 and 25 (battery and ignition supply)were both present and the module was found to be grounded satisfactorily through pin 11.
Onto the can bus system pins 9 and 10 (can high and can low) which were both ok, the checks performed so far would indicate probable module failure. After consulting the customer the decision was taken to replace the module, upon installation i was pleased to see that the fault was now rectified and all three warning lamps extinguished after starting.
I have to say this case posed a few problems for me with regards to obtaining a wiring diagram for the four wheel drive system, it was absent from all our usual technical sources but with help from alldata i managed to obtain the relevant document, without this information diagnosis of this problem would have being much more difficult.