Please Help - Relay Probs
Thread Starter
|
New User
Joined: Jan 2006
Posts: 7
Likes: 0
Please Help - Relay Probs
The scenerio: Every few weeks, I go out to start my truck and it won't start. I noticed thr 30A PCM fuse is blown. I replace it and the 2 relays - PCM and Fuel . She starts right up. I just can't figure why its happening.
The diagnoses:
From the fuse box I first checked the relays..
Inertia Switch Off and Key On.
PCM = 86 to 30 = 12v and 86 to 85 = 12v
FPR = 87 to 30 = 12v and 86 to 30 = 12v
PCM 30A fuse = Ov
Inertia Switch On and Key On.
PCM = same
FPR = same
PCM 30a fuse = same
Inertia Switch on. Key Off.
PCM = same
FRP = same
PCM 30a Fuse = 12V
Put in 2 new relays...key off...PCM 30A fuse = 12V
Should there be power across the fuse when the truck is off?
97 Ranger Super 2.3L
And the FPR (fuel Pump relay) clicks when bridging the PCM fuse with brand new relays installed.
The diagnoses:
From the fuse box I first checked the relays..
Inertia Switch Off and Key On.
PCM = 86 to 30 = 12v and 86 to 85 = 12v
FPR = 87 to 30 = 12v and 86 to 30 = 12v
PCM 30A fuse = Ov
Inertia Switch On and Key On.
PCM = same
FPR = same
PCM 30a fuse = same
Inertia Switch on. Key Off.
PCM = same
FRP = same
PCM 30a Fuse = 12V
Put in 2 new relays...key off...PCM 30A fuse = 12V
Should there be power across the fuse when the truck is off?
97 Ranger Super 2.3L
And the FPR (fuel Pump relay) clicks when bridging the PCM fuse with brand new relays installed.
Last edited by ralphwolf; Jan 24, 2006 at 10:26 AM.
Postmaster
Joined: Oct 2003
Posts: 4,516
Likes: 1
From: SoCal
Unfortunately, voltage from the PCM power relay splices to injectors/pump relay/cam sensor etc etc.
It also splices to the O-2 sensors.
Take a look at the wiring to the O-2's & make sure it's not shorting out..
Got a wiring diagram????
It also splices to the O-2 sensors.
Take a look at the wiring to the O-2's & make sure it's not shorting out..
Got a wiring diagram????
Last edited by 87 XLT; Jan 24, 2006 at 01:46 PM.
Postmaster
Joined: Oct 2003
Posts: 4,516
Likes: 1
From: SoCal
Is the fuse blowing as soon as you replace it now, or still "every few weeks?"
Theres should be a couple of connectors that you can open up & see if the fuse still blows, but I dont have a wiring diagram for a 2.3.
And yes the fuse for the power relay is hot all the time.
Theres should be a couple of connectors that you can open up & see if the fuse still blows, but I dont have a wiring diagram for a 2.3.
And yes the fuse for the power relay is hot all the time.
Thread Starter
|
New User
Joined: Jan 2006
Posts: 7
Likes: 0
Fuse
It blows every few weeks (4 times in all).
3 - when I went to start it...nothing but turn.
1 (last night-my wife) - she made a turn and hit the gas and it happened.
I have been replacing both relays and the fuse to get it to work. But, after tinkering more today...the relays might not be actually bad. I checked them by turning the key and inserting them to hear them engage. I also popped them open to see if they were stuck...they all looed good (7 of them)
3 - when I went to start it...nothing but turn.
1 (last night-my wife) - she made a turn and hit the gas and it happened.
I have been replacing both relays and the fuse to get it to work. But, after tinkering more today...the relays might not be actually bad. I checked them by turning the key and inserting them to hear them engage. I also popped them open to see if they were stuck...they all looed good (7 of them)
Trending Topics
Postmaster
Joined: Oct 2003
Posts: 4,516
Likes: 1
From: SoCal
I'm looking at the wiring diagram for a 97 4.0 -should be similiar to yours-and theres no place where the wiring goes thru sheet metal that might be shorting out.
So the problem is somewhere under the hood. Also theres only one fuse after after the PCM power relay, which is between the relay & the O-2's so disregard what i said earlier about checking the O-2 wiring.
Have you tried doing a "wiggle test" on the wiring? If you can get the fuse to blow that will get you in the ball park.
It would sure help if it would just short out & stay that way.
So the problem is somewhere under the hood. Also theres only one fuse after after the PCM power relay, which is between the relay & the O-2's so disregard what i said earlier about checking the O-2 wiring.
Have you tried doing a "wiggle test" on the wiring? If you can get the fuse to blow that will get you in the ball park.
It would sure help if it would just short out & stay that way.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Postmaster
Joined: Oct 2003
Posts: 4,516
Likes: 1
From: SoCal
It's hard to tell from the diagram that i have, but it looks like the "canister vent solenoid" is located under the floorboard drivers side below drivers seat.
Red & purple/white wires
Other than that, everything thats wired to the PCM relay is under the hood.
Red & purple/white wires
Other than that, everything thats wired to the PCM relay is under the hood.