Tranny get lock

[matuva]

A buddy of mine called me for advice : few times ago, some troubles appear:

His truck is a Cheyenne K1500 from 1996 with 6.5.

this started with engine iddling up and down at cold start;

then, ABS light start lighting up (seems it is due to right hub assy)

This past week-end, they change the actuator and put a 1997 actuator with harness "k" to make it fit on his 1996.

Don't know for sure if it is the culprit, but it a fact that now, the tranny stays locked on 1st.

Here are the symptoms:

- the pump light on dash lights up;

- engine runs fine, tach goes up and down then loose, though driving speed stays study;

- gear box stays on 1st, doesn't engage to 2nd and up. Seems sometimes it tries and makes lot vibrations.

I will meet him this evening and see what codes and I can get from ECM.

Any idea?

[JohnC]

Need those codes.

Whenever the trans has a problem shifting or detects a problem with the shift circuitry, it defaults to second gear. This is often confused with first gear. If you can go faster than about 15 mph, it's second, not first.

A common cause is problems with the power to that circuit, which is controlled by a separate set of contacts in the ignition switch. Monitor the voltage at the trans fuse. If it ever drops below 9 or 10 volts, this is likely your problem. but, we need the codes...

[matuva]

Hi,

thank you for replying.

We found no codes except 404 and 1655, but these are related to EGR

[JohnC]

You're going to have to put a scanner on it to figure out why it's not shifting. With no codes set, the PCM must think it's not supposed to shift...

[matuva]

My buddy phoned the dealer and he succeed in having an appointement this wenesday. We'll know more after.
For now, we're wondering about speed sensors. Anybody knows how to test them?