Pcm

[CowboyX]

If I disconnect my PCM will it lose it's programming?

[DmaxMaverick]

No. It'll be no different than disconnecting the batteries (which should already be done, BEFORE disconnecting the PCM). Be careful of the connectors, though. They can be easily damaged, and difficult to repair. Make sure they stay aligned, coming off and going on.

[Artworks]

If it is early on, OBO1, it have to "relearn" glow cycle. ( mine does whenever batteries are disconnected)

[CowboyX]

No it's a late 96 OBD2. It looks like the bottom of the PCM is coming off and the whole unit is loose. I'm trying to resolve a no power issue. I find that if I depress the accelerator as little as possible the truck seems to run better, but I still get a po 1656 code. What I really need is a snap on scanner

[DmaxMaverick]

P1656 is a wastegate solenoid fault code. Very unlikely a PCM issue, but is probably the cause of your power and throttle position issue. Verify the solenoid is seeing full vacuum pump vacuum, and the WG actuator is holding the WG firmly closed at idle. It often helps to remove the solenoid and flush it well with WD40. A failed solenoid is not uncommon, but vacuum leaks are more frequent.

[CowboyX]

Here's the funny thing, when I use the old solenoid I get full vacuum at idle, however when driving the solenoid see vacuum all the time and the truck runs worse so I think the old solenoid is stuck open. When I use the new solenoid I don't have vacuum at idle but when driving it ranges from 2 psi to 8 psi or so and the truck seems to run and shift better.

[DmaxMaverick]

A few possibilities here:

-Failing vacuum pump. Requires higher engine RPM to produce acceptable vacuum. It should hold a steady (very little, if any, fluctuation) minimum 20" Hg at idle. A new pump should ideally produce 24-26" at idle. This vacuum should be modulating (by the WG solenoid) to a steady 15" at the WG actuator.

-Vacuum system leak(s). Requires higher engine RPM for the vacuum pump to provide acceptable vacuum. This is the most common issue with older vehicles.

-Incorrectly connected solenoid, or improperly routed vacuum lines. It only works one way.

-Bad "new" solenoid. It happens. At engine idle, the WG actuator should be receiving vacuum, solenoid failed open or not.

[CowboyX]

I was looking at my PCM and I found a 3 wire connecter with what looked like 2 black and 1 red wire one one side of the plug and 1 small black 1 black the same size as on the other side and a red. The plug was melted where the 2 black wires are. I'm going to have to remove the plug and replace it with single wire plugs. The plug was marked with " ABC "
P.E.D.5
I don't know if this has anything to do with the PCM but melted wires are never a good sign.
Also I couldn't get the PCM out from under the dash, I can see to screws the hold it in place on the inside of the truck and what looks like another at least 1 more screw on the other side. How do I remove it from a 1996 Silverado?

[CowboyX]

If I drive with a heavy foot I get the following codes:236,238,406,1656