99 Escalade Fuel Pump Relay No Power: Troubleshooting Without Check Engine Light or Codes
I own a 1999 Cadillac Escalade and am experiencing a fuel pump relay issue. I've replaced the fuel pump, filter, and relay, but there's still no power reaching the fuel pump relay circuit. No diagnostic codes are appearing, and the check engine light is not on. All other relays in the relay box under the hood receive power when the key is in the 'on' position. A circuit tester shows positive voltage at all terminals for those relays, but the fuel pump relay consistently lacks power—neither receiving input nor sending output. I've checked all fuses and confirmed they are intact and properly seated. No visible wire damage or corrosion is present. The issue appears to be downstream of the power supply, possibly involving the ECU/PCM. However, before replacing the PCM, I'd like to confirm if there are any other potential causes. Could it be a wiring harness issue? A faulty ground connection? Or could the problem lie in the ECU's fuel pump relay control signal? Any insights or testing procedures from others who've faced this exact scenario would be greatly appreciated.
Some key points to consider: > The fuel pump relay only energizes the pump for approximately 3 seconds when the engine won't start. > Is there a security light (or immobilizer) present? If not, that could be a factor. > Does your vehicle have a remote starter system? > Which specific terminal on the fuel pump relay shows no voltage when the key is in the 'off' position (KOEO)? > Are you using a dual-fuel tank setup? This can affect fuel delivery and relay behavior.