New owner need info
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Heel & Toe
Joined: Mar 2021
Posts: 18
Likes: 1
New owner need info
I have codes p1518 and p0650 From what I understand p1518 is related to the TAC? I however don't ever go in reduced power mode but I do notice a little bit of throttle lag sometimes. As far p0650 I have no clue something to do with the check engine bulb or wire from what I understand? All the information I can get from you guys would be highly appreciated! I am a new c5 owner and am just running into a boat load of problems.
Drifting
Joined: May 2007
Posts: 1,547
Likes: 210
From: Huntersville, NC
the p0650 is related to the check engine light circuit. the p1518 is related to the TAC module, probably a broken wire or bad connection.
As a SWAG, I might [guess] that there is a bad connection at the TAC module or the PCM. Both these modules are behind the RF fender, and in the trajectory of battery acid, as the battery resides above these two modules.
So my SWAG is either acid got to a couple of wires, or mice got in the area, as it is easy for them to get there and they love to chew on wire insulation.
You can access the connectors by removing the RF tire, and the rear inner fender liner. There are 3 screws under the car that need a 7 mm socket that are very hard to see if you don’t have a lift. So, once the inner fender is out, you will just be able to see the TAC connections and PCM connections. There are two connectors on the TAC module, the bigger one has 16 pins and is the connector that would be involved in the p1518 code. There are two long rectangular connections on the PCM, and I’m not sure which one would possibly be involved with the p0650, so A good look for any wire damage or battery acid damage would be a start.
If it were my car, I would pull the RF fender to see if I there is any evidence of battery acid damage, I would then remove the TAC and PCM and carefully go through the wires and connectors, cleaning and neutralizing any acid residue. It is easy to bend a pin on the PCM connectors, especially if you work them with the fender still on.
I’m going to guess that your pcm is ok, and it is responding to those codes by pulling timing and fuel delivery, making the car seem sluggish. You need some more TAC codes to show before true limp mode happens. Likewise, for now, assume your TAC is ok and focus on wires and the connectors. The contacts in the connectors need to be clean and make good mating connection.
As a SWAG, I might [guess] that there is a bad connection at the TAC module or the PCM. Both these modules are behind the RF fender, and in the trajectory of battery acid, as the battery resides above these two modules.
So my SWAG is either acid got to a couple of wires, or mice got in the area, as it is easy for them to get there and they love to chew on wire insulation.
You can access the connectors by removing the RF tire, and the rear inner fender liner. There are 3 screws under the car that need a 7 mm socket that are very hard to see if you don’t have a lift. So, once the inner fender is out, you will just be able to see the TAC connections and PCM connections. There are two connectors on the TAC module, the bigger one has 16 pins and is the connector that would be involved in the p1518 code. There are two long rectangular connections on the PCM, and I’m not sure which one would possibly be involved with the p0650, so A good look for any wire damage or battery acid damage would be a start.
If it were my car, I would pull the RF fender to see if I there is any evidence of battery acid damage, I would then remove the TAC and PCM and carefully go through the wires and connectors, cleaning and neutralizing any acid residue. It is easy to bend a pin on the PCM connectors, especially if you work them with the fender still on.
I’m going to guess that your pcm is ok, and it is responding to those codes by pulling timing and fuel delivery, making the car seem sluggish. You need some more TAC codes to show before true limp mode happens. Likewise, for now, assume your TAC is ok and focus on wires and the connectors. The contacts in the connectors need to be clean and make good mating connection.
Last edited by k24556; Apr 13, 2021 at 07:35 AM.
