[Killer_19]

I bought a 01 rt a few months ago and it had 3 o2 sensor heater codes. I replaced the fuse and o2 sensors and the codes went away. But it didn’t last long, after a few days the drivers side front says that the voltage is too high. I don’t care about the light on the dash more the fuel economy. I’m not sure what it could be because it’s only one code and I know the o2 sensor is good. Is there a way to test the wiring? Also I have an intermittent brake and abs code for a bad relay. Sometimes it dosent come on at all, sometimes it goes away after starting to drive and some times it won’t go off, but if I restart it it usually goes away. I would replace the relay but it is built into the module and from what I know can’t be replaced separately and a new module isn’t cheap, any ideas on what it could be?

 

[immattj]

Also I have an intermittent brake and abs code for a bad relay. Sometimes it dosent come on at all, sometimes it goes away after starting to drive and some times it won’t go off, but if I restart it it usually goes away. I would replace the relay but it is built into the module and from what I know can’t be replaced separately and a new module isn’t cheap, any ideas on what it could be?

The code is specifically for relay??
A steady red brake light & an amber ABS light could be caused from (among other things) the rear speed sensor (mounted on the rear diff). I am not at all familiar with that relay you are referring to.

A while back ago I was on a thread related to the cause of those two lights being on & I posted what the FSM said about possible causes. I'll see if I can find that thread & I'll provide a link for you.

 

[immattj]

. . . this is one of the threads on the subject (of the brake & ABS lights)

2001 Dakota has gremlins

Can't find the flasher turn signal relay. YouTube not much help. When I start it, I get a ABS and emergency brake light and the AC, odometer and speedometer don't work. After driving for some time the lights go off and AC, odometer and speedometer start working. Turn it off and all problems...

www.dakota-durango.com

but this is the information from that thread that would be pertinent to that particular issue:

The FSM attributes a flashing red brake light as being due to "a vehicle tooth or tire parameter is faulty or missing" vs a steady red being due to "when a system malfunction exists." Also, a steady red for 3.4 seconds during an initial test at the beginning of the ignition cycle.

the CAB (controller Antilock Brakes) can signal the operation of both the ABS light and the red brake light via the PCI bus.

"The Instrument Cluster controls the [ABS light]. All Dodge Truck Instrument Clusters have direct control over the [ABS light and red brake warning light]"

The Instrument Cluster.controls the red Brake warning light. There is a parallel path to chassis ground that will illuminate the red Brake warning light:
through parking brake switch contacts
through brake fluid level switch
through the CAB via PCI Bus.

The red Brake warning light is to alert the driver of:
brake fluid low
parking brake applied
ABS system malfunction.

 

[Killer_19]

The code is specifically for the relay. I believe it is located in the “CAB” AKA the abs module. In order to replace the relay though you have to buy the whole module which is what I am trying to avoid.

 

[immattj]

The code is specifically for the relay. I believe it is located in the “CAB” AKA the abs module. In order to replace the relay though you have to buy the whole module which is what I am trying to avoid.

That's interesting. Must be code 65 "internal main relay open" or 66 "internal main realy shorted"?

Depending upon voltage & resistance measurements on troubleshooting, the '03 FSM is saying to look at & clean the CAB connector & to inspect the wiring harness itself before changing the CAB.

 

[Killer_19]

The code is 65 which my scanner says is open relay. There is another code which is 74 and says “sys ctrl mode timeout”. I didn’t see any problems with my wiring harness when I looked but I also didn’t look that well. I will check everything out when I get home. Is there a recommended way to clean the connector?

 

[immattj]

Going by the pictures, depending upon which CAB you have, it looks like it could be one connector or two connectors. If the '01 is the same as the '03.

As far as cleaning, I would assume getting a spray can of electronics cleaner& giving both the male & female ends a real good douch. Who knows, sometimes just unracking & reracking a connector "fixes" things.

On the code 74, the FSM is listing for possible causes:
tone wheel damage/missing
foundation brake faults
wheel bearing loose/binding
wheel speed sensor concern
CAB - no response to input
brake lamp switch
brake lamp switch sense circuit
CAB - internal fault

I'll do some scanning & I'll attach the trouble shooting sequences for both codes; code 65 will have you checking some stuff with a multimeter. I am really not very good at doing stuff on a computer, so it may come in multiple posts.

 

[immattj]

This should be 65

 

[immattj]

This should be 74.
My standards are not all that high, so if it was me & it wasn't something cheap & easy I would live without ABS (as a matter of fact, on one of my picups I am living without ABS).
Good luck!

 

[Killer_19]

Thanks for all the info. If it’s not something simple I probably won’t mess with it but I am trying to sell it soon so I want to get rid of as many lights as possible.

 

[immattj]

Sure thing. If you do wind up replacing the CAB, the FSM is saying it that it has to be programmed for your axle & tire size.
And if you spray the inside of your connector(s?) down with electronics cleaner, give it a few minutes to dry. It evaporates real quickly, but still I didn't wait long enough a couple of times & I actually had a PCB short out & catch fire and one I had a switch I had soldered short out to the immediate 'ON' position when I plugged it in (it was a high speed grinder & it got my attention).

You must have a pretty good scanner to be reading the codes on your PCI Bus modules?
It could probably do the programming on your CAB if you do wind up changing it?

 

[herbS]

I bought a 01 rt a few months ago and it had 3 o2 sensor heater codes. I replaced the fuse and o2 sensors and the codes went away. But it didn’t last long, after a few days the drivers side front says that the voltage is too high. I don’t care about the light on the dash more the fuel economy. I’m not sure what it could be because it’s only one code and I know the o2 sensor is good. Is there a way to test the wiring? Also I have an intermittent brake and abs code for a bad relay. Sometimes it dosent come on at all, sometimes it goes away after starting to drive and some times it won’t go off, but if I restart it it usually goes away. I would replace the relay but it is built into the module and from what I know can’t be replaced separately and a new module isn’t cheap, any ideas on what it could be?

I bought a 01 rt a few months ago and it had 3 o2 sensor heater codes. I replaced the fuse and o2 sensors and the codes went away. But it didn’t last long, after a few days the drivers side front says that the voltage is too high. I don’t care about the light on the dash more the fuel economy. I’m not sure what it could be because it’s only one code and I know the o2 sensor is good. Is there a way to test the wiring? Also I have an intermittent brake and abs code for a bad relay. Sometimes it dosent come on at all, sometimes it goes away after starting to drive and some times it won’t go off, but if I restart it it usually goes away. I would replace the relay but it is built into the module and from what I know can’t be replaced separately and a new module isn’t cheap, any ideas on what it could be?

I have an 01 DD that was bought new w/ 178K and it still runs great, keep'em serviced boys! I've had that code a few times before in the last 20 years. The problem turn out to be dry rot vacuum
hoses once. don't overlook them. And make sure to shut truck before pumping gas into it.