The speedometer started jumping erratically when driving and then finally quit completely. Check engine light now stays on, but vehicle seems to still run OK. Dealer swapped in a new speed sensor and said it didn't fix the problem and said I have a signal going to the ECM so problem is within the ECM or between the ECM and the cluster. I see there are many other posts related to various Isuzu speedometer failures. Should I buy a salvaged ECM and try replacing mine or try a replacement instrument cluster? Would a service manual tell me what wires/terminals to measure to isolate problem? Could the problem be related to a service bulletin I found for 1998 amigos/rodeos to an improperly crimped ground wire be the problem? (Remedy in bulletin is to replace the wiring harness).
Dec 14, 2009 at 10:04 AM