Archived 02 in limp mode

[dcamilleri]

I am trying to help a friend out of a bind. He has an 02 HO 6speed that went into limp mode this morning. I hooked up my scan tool and pulled lots of codes: PCU 1693, P0121, P0562, P0575, P0606, P0342, P0117, P0112, P1488, P0237. I ran a data stream and got 0 voltage reading for battery voltage, 0 volts for engine temp, (but engine temp registered 188deg) 0 volts for oil pressure. The temp gauge on the dash is burried on the hot side and when I checked setting through another setting it showed 293 deg. (according to pcm) TPS voltage is normal and changes with the throttle. I cleared codes and they came right back. I cleaned battery connections and checked grounds. I disassembled connectors to ecm/pcm on main wiring harness and applied dielectric grease. I disconected plug to coolant temp sensor and then the scan tool would show 5volts, engine would surge bad. With key on and engine off scan tool would show actual battery voltage but as soon as engine is started battery voltage on scan tool would drop to 0. Actual battery voltage at the batteries is 14+ volts. Engine revs very slowly and won't rev past 2000 rpms. I am pretty sure it is in limp mode. He has a power puck and I disconnected it for all tests. Anyone seen this before? Truck has 36,240 miles. Thanks for any ideas in advance. Dave

 

[Sticks]

I would check the wire harness connections to the ECU and the PCU. Too many codes for too many unrelated items to be a massive sensor failure.



Either the Alt went haywire and fried the elelctricial system, or one of the computer connections came loose or got wet.



Then start checking all the majior wire harness connnections (by the firewall above the valve cover, under the dash,... )



If all the connections are good, I would start loking to see if it is the ECU or the PCU has gone TU.

 

[dcamilleri]

Sticks,

I agree with you, I have already checked most of the wiring conections. The weird part is that the scan tool isn't picking up battery voltage with the engine running, but with engine off and key on it will show battery voltage. Problem started right after a small rain storm, so I am still thinking bad connection somewhere. The engine tempature guage being pegged still bothers be though. Time for some more research.

 

[dcamilleri]

I think I will change my opinion. I didn't look closely at the P0606 code yesterday. I checked and it points to a ECM failure and would explain all the other codes, most of which are for low voltage where a 5 volt signal is supposed to be. So off to the dealer for an ECM under warranty.

 

[dcamilleri]

Dealer agrees and had new ecm on order. Hope his power puck did not cause this.