Stumped???

[broken6.5]

Need some help. Installed a new IP on a 99 6.5 (F). Went to check timing with the computer(Snap On MODIS), did KOKO, timing is advanced to 14.00 due to the ECT feed stating coolant temp is -40. Replaced ECT sensor on top of engine. No change. Traced black and yellow sensor wires back to the ECM, both are acceptable. No apparent shorts to neighboring terminals. When running, the engine really does not like the black and yellows jumped(closed), stumbles when removed removed from the sensor (open). Pump is static mounted correctly.

Any ideas on next steps???? Thanks

 

[diesel65]

When you jumped the ECT connector what was the engine coolant temp reading on the MODIS?

 

[broken6.5]

It was last week, but I think it never changed from -40. Timing went haywire though.

 

[diesel65]

When you jumped the ECT connector, the temp should have maxed out on the hot side. It seems that you have an open circuit.
When you traced the wires, did you do a continuity check from the ECT connector to the PCM on each wire?

 

[broken6.5]

Yes, yellow on connector to C11 on PCM. Black to B12. Had cont.

 

[bk95td]

I wouldn't trust the snap-on scan tool on a 6.5. They have been known to not read correctly. I had one cost me close to $700 in parts that weren't bad. Check against another scan tool .

 

[Turbine Doc]

X2 on the Snap On scanner, I had to verify my MT2500 vs a GMT2 to know what the TDCO value was, it was WAAAY off. my 96-98 cartridge for a -1.94 TDCO is -5.4 offset reading, on my 96-2001 cartridge it's a little closer but still out -1.94 = -.9 n I'm good with that knowing what I know about it, but I suspect many shops using a Snap on scanner have had time setting issues, the TDCO is the only error reading I have found.

When talking to Snap-On about it the knew there was an issue, and supposedly the MT2500 replacement was supposed to correct the issue, I'd compare it to a GM T2 or a good T2 clone tool 1st to make sure it match before relying on it.

TMHarks IP was set with one of the newer Snap On tools I think, his timing was out of whack when I visited him a couple of weeks ago, after setting his IP with my "adjusted/compensated" TDCO reading offset, his heavy smoke cleared, his codes, and he had a less pronounced "rattle" at cold start-up than with the newer tools reading.

 

[NVW]

The -40 temp is a signal from the sensor in the thermostat housing, not the one in the head. Hope that helps.

 

[broken6.5]

Update for those keeping score at home: 2 different Modis' = no ECT reading(-40). A third Modis and a MAC Navigator= 199*F. Thanks for the help!