OK. I just got those codes checked.
C1187 - DIFF LOCK CONTROLLER
P1839 - POSI SWITCH ON
Here's a written summary of what was done:
"Tech checked for TSB's, but none were found.
While performing test on Differential Lock Switch is intermittently out of specification.
Reference values for Differential Lock Control Unit are as well out of specifications.
More diaganosis time is needed to find fault.
At this time, we are unsure as to what is causing concern. Technician will attempt to call tech-line for possible solutions but more diagnosis time is necessary to verify fault."
When I left the dealership, all the lights had stayed off for my 30+ mile drive to work and they are currently still off. However, I am not confident that they will not come back on.
When I brought my truck to the dealer this morning, they told me it would cost be $85 for diagnostics. After an hour looking at it, I was informed that it would be an additional $85/hour for them to continue to look at it. However at this time, they have no idea what it could be.
Before I throw any more money at them, I would like to see if you may have heard of this problem so that they could shortcut their diagnostics time. I don't want to pay them to conduct a research project for someting that may have already been thoroughly researched by someone else.
I hope you can help! Thanks!