Will not crank

1999 CADILLAC DEVILLE

110,000 MILES • 4.6L • V8 • 2WD • AUTOMATIC

MALONE01

MEMBER
3 POSTS

The car will not start. there is only the check engine light on, on the cluster everything else does not work on the cluster, and the radio display says lock. Can you tell me what direction to go as far as making the car start turn over?

May 9, 2019 at 2:11 AM

SCGRANTURISMO

✓Experienced Mechanic
4,897 POSTS

Hello,

Can you pull the Direct Trouble Code(s)(DTC)(s) for me? You will need a code reader to do this and I have included a link below for you to go to if you are unfamiliar with how to do this.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please get the DTC(s) and get back to us with what they are.

Thanks,
Alex
2CarPros

May 9, 2019 at 3:24 AM

MALONE01

MEMBER
3 POSTS

The codes are P0603 and P1604.

May 10, 2019 at 2:41 AM

SCGRANTURISMO

✓Experienced Mechanic
4,897 POSTS

Hello again,

Here is the information that you requested on both DTC's P0603 and O1504. Please go through these guides and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

Images (Click to enlarge)

May 10, 2019 at 8:46 AM

MALONE01

MEMBER
3 POSTS

I think the PCM module is bad.

May 10, 2019 at 9:19 AM

SCGRANTURISMO

✓Experienced Mechanic
4,897 POSTS

Hello again,

Okay. Just to be sure it's not just a bad ground, I have included a PCM wiring diagram as well as a factory PCM Ground and Power Troubleshooting Guide in the diagrams down below. A bad ground can cause a variety of problems, and a new PCM would make no difference with a bad ground, so let's check it out to make sure. Please go through the guide and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

Images (Click to enlarge)