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Im in the process of installing a full Autometer gauge cluster as well as warning lights.
For the pin-out in my truck there's Two seperately wires.
#1. PIN number 9 on the C251 clip. (PK/LG) "Check Engine" Input from EEC
#2. PIN number 12 on the C251 clip. (W/R) "Engine Warning" Input
This confuses me because both are inputs.
Which one do I use to hook my aftermarket check engine light to?
If it makes a difference, all wiring that's being used for this project has been de-pinned from the harness clip and the leftovers have been left in the clip and tucked away in case for some reason the factory cluster ever has to make its way back in.
Thanks in advance. I'm documenting everything just in case somebody wants a write up on it. I know there's not much out there for the 1987-1991 style.
Thanks subford. Sadly I have that diagram but did not catch it. I probably should get some lights wired up to 12 however that's what the gauge's are for and I don't want the new cluster cluttered up with things that I really don't need. I'd like it to stay all business so to speak.
My apologies for the low quality cell phone pic. Just a quicky.
Ill have better quality to post up if ever needed in the future.
On the 87 to 91 cluster's there is a "Check Engine" light for when the temp is high and/or low oil pressure. That is driven off a small PC board attached to the instrument cluster on my truck(89 F250). That PC board monitors the temp and oil sensors and will turn on that light in the cluster.
The way those indicator lights are located, they are not very noticeable..... I like the 80 to 86 indicators that are on top of the cluster and are very noticeable.
On the 87 to 91 cluster's there is a "Check Engine" light for when the temp is high and/or low oil pressure. That is driven off a small PC board attached to the instrument cluster on my truck(89 F250). That PC board monitors the temp and oil sensors and will turn on that light in the cluster.
The way those indicator lights are located, they are not very noticeable..... I like the 80 to 86 indicators that are on top of the cluster and are very noticeable.
Hmm, never noticed them! How about the emergency brake light. I know the master cylinder in my truck was low at one point and kicked that perticular light on, but when I used my emergency brake, I never seen a light for it.
Also, I've heard something about having to loop the charge wire or something because other wise the alternator will not charge?
I used to have an 84 bullnose some years back that I did the same cluster mod too. I love being able to utilize the accuracy of the aftermarket gauges. I've always felt that was one of the short comings of these trucks. I must say that I did like the dash a bit more on the 84 AFTER the new gauges were in vs the 91's. Hopefully Ill like the 91 that much more.
I think I still have a fairly large thread on the removal of the smog equipment on the 460 in that section.
I wanted to get this done now because hopefully next year I'll have either a big block, or coyote going in this thing and I'd like the truck to be 100% ready for it so there's nothing left to do.
After the motor, trans and rear are done, I'll simply purchase and swap out a new speedo with 0 miles on it. Autometer informed me that they can add miles to the new speedo to match the old one so you can keep your miles accurate, however they can not reprogram for less milage. Strange.
Hmm, never noticed them! How about the emergency brake light. I know the master cylinder in my truck was low at one point and kicked that perticular light on, but when I used my emergency brake, I never seen a light for it.
Also, I've heard something about having to loop the charge wire or something because other wise the alternator will not charge?
After the motor, trans and rear are done, I'll simply purchase and swap out a new speedo with 0 miles on it. Autometer informed me that they can add miles to the new speedo to match the old one so you can keep your miles accurate, however they can not reprogram for less milage. Strange.
The park/emergency brake pedal is tied into that same light as the low brake fluid light in the cluster. Most likely that connector fell off or that switch is bad. It's located inside the park brake pedal assy inside the truck.
Yes, you will have to use the battery/charge lamp indicator to allow the alternator to charge. It is a special lamp socket with a 520ohm resistor across the lamp. Or you can just tie that wire to switched power(run) so the charging system works. That is a issue in the 92 to 96 trucks when others swap out clusters between years. Different years have different pin-outs on the clusters and causes a no charge problem along with a few other issues too.
As for Autometer programming in mileage, as long as you document the mileage, they will run the new odo up, BUT they will NOT make is less, that's odometer fraud and the feds do not like that al all! So if you get a new odometer reading with 0 miles, you best put a sticker on the door pillar telling others that mileage is not accurate. But if you are never going to sell the truck, I would not worry about it.
Use pin #9 on C251 plug.
Pin #12 is for low oil pressure or high engine temp.
Heres another one for ya. Getting close to being done with this.
I've noticed all of the wires for my indicator/ warning lights are 14-16 gauge.
Why is the Amp Indicator Input (Pin#14 on C251 R/LG) a thicker wire?
It is an indicator light after all.
I don't want to hook this up to an indicator if its going to cause an issue.
This will be used for the Battery/Alternator Warning light.
Also, is this the same wire that I have to run a switched power source to? Even if im utilizing it right at the harness clip and the wire hasent been cut anywhere?
Thanks again for all the help.
Pin#14 on C251 R/LG wire #16, it is a 12GA wire.
Wire #16 is a main feed wire to the Ignition system and other systems.
It splices and branches to other devices also.
It is powered by the Ignition Switch.
Wire #16 is 12GA to all of its points as it is only protected by a Fuse link at the starter solenoid/relay.
You must have a wire larger than its protective device or you would have a fire.
The wire leaving the charge indicator is a 18GA wire as it does not use much current, it is wire #904 a LG/R wire.
Pin#14 on C251 R/LG wire #16, it is a 12GA wire.
Wire #16 is a main feed wire to the Ignition system and other systems.
It splices and branches to other devices also.
It is powered by the Ignition Switch.
Wire #16 is 12GA to all of its points as it is only protected by a Fuse link at the starter solenoid/relay.
You must have a wire larger than its protective device or you would have a fire.
The wire leaving the charge indicator is a 18GA wire as it does not use much current, it is wire #904 a LG/R wire.
I hope I'm understanding this correctly. Please forgive my ignorance.
Ok, so I would use #904 for the check engine light indicator even though its an output rather than an input?
Also, which to wires do I splice together to avoid charging issues.
I really appreciate your help man. Thank you very much.
Wire #904 is only used to turn on the alternator.
The diagram below is for the check engine light indicator.
Pin number 17 of the PCM. Attachment 281523
11-23-2018, 03:41 PM
