P0688 on RAM
ECM/PCM Power Relay Sense Circuit/Open
P0688 on RAM vehicles indicates ecm/pcm power relay sense circuit/open. Au7o has documented this code across 1 RAM model — most commonly on 2500. An open or general fault in the sense (feedback) circuit the module uses to verify the ECM/PCM power relay output. The module cannot confirm relay power is present. Typical repair costs on RAM range from $300 to $1,200, depending on the specific model and root cause.
Common Causes of P0688
- •Open in the power relay sense circuit
- •Faulty ECM/PCM power relay
- •Corroded/damaged connectors
- •Blown fuse on the sensed feed
- •Internal PCM fault
P0688 on RAM by Model
RAM 2500(1 issue)
- TIPM (Totally Integrated Power Module) Failure2006-2018
The TIPM is the central under-hood fuse/relay and power-distribution computer that controls the fuel pump, lighting, wipers, door locks, horn, and trailer-tow circuits. It is a widespread failure point on 2007-2016 Ram trucks. The most common complaint is the internal fuel pump relay sticking: stuck ON causes overnight battery drain and the pump running with the key off, while stuck OFF causes intermittent no-start / stalling. Other failures include inoperative wipers, dead door locks, non-working turn signals/high beams, phantom horn, and dead trailer lights. Root causes include water intrusion into the layered module and improperly spliced aftermarket accessories overloading circuits.
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View P0688 across all makes →Frequently Asked Questions
What does P0688 mean on RAM?▼
P0688 stands for "ECM/PCM Power Relay Sense Circuit/Open." An open or general fault in the sense (feedback) circuit the module uses to verify the ECM/PCM power relay output. The module cannot confirm relay power is present. On RAM specifically, this code is documented across 1 model.
What causes P0688 on RAM vehicles?▼
Common causes on RAM: Open in the power relay sense circuit, Faulty ECM/PCM power relay, Corroded/damaged connectors, Blown fuse on the sensed feed, Internal PCM fault. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0688 on a RAM?▼
Repair costs on RAM range from $300 to $1,200, depending on the specific model and root cause.
Which RAM models have P0688 documented?▼
Au7o has documented P0688 on 1 RAM model: 2500.