Electrical Questions

Hello again my friends. I'm writing today to see if I'm on the right track with a few electrical issues. Bear with me as I'm trying to make this make sense.

I've chased down (with several forum members help) four or five issues I had been having. I'm down to the last two.

1) I still have an intermittent airbag light. I pulled the dash cluster out and cleaned and greased the cluster connections with no luck. The clockspring was recently replaced as well. That fixed my cruise and my horn, but not the airbag light. It's still coming on every few minutes.

My Airbag Control Module has been relocated and the connections to that seems fine as well. Wiggling the connector has no effect.

So, I've been searching and reading. I found a message on another board that referenced a fusible link in the engine compartment. Long story short, the OP stated that there is a 40 amp fusible link that was the culprit. Per his message, the mechanic he took his jeep to---his was 97, mine 99, so comparable---said that this link also powers the auxiliary fan.

Light bulb! I have disconnected my aux fan since it stopped working a while ago. (Which happens to be issue # 2).

Per the article I was reading, the mechanic said if the aux fan fails it can overload this link, causing a variety of electrical issues. Anyone have an idea what he is referring to?

Also, I'm pretty sure the reason my fan failed was due to my A/C being completely empty--no pressure. Likely issue there is the evaporator. :doh:

So, here's my thought. My A/C system leaks out, fan fails causing this link to fail, causing the airbag light to make my blood pressure spike.

If I'm an idiot...don't be shy. Thanks!

BTW

Here's a link to the article I was reading.
http://www.jeepforum.com/forum/f11/airbag-dash-light-663344/index2.html
Posts # 18 and 21.

wolfman_023 said:

Hello again my friends. I'm writing today to see if I'm on the right track with a few electrical issues. Bear with me as I'm trying to make this make sense.

I've chased down (with several forum members help) four or five issues I had been having. I'm down to the last two.

1) I still have an intermittent airbag light. I pulled the dash cluster out and cleaned and greased the cluster connections with no luck. The clockspring was recently replaced as well. That fixed my cruise and my horn, but not the airbag light. It's still coming on every few minutes.

My Airbag Control Module has been relocated and the connections to that seems fine as well. Wiggling the connector has no effect.

So, I've been searching and reading. I found a message on another board that referenced a fusible link in the engine compartment. Long story short, the OP stated that there is a 40 amp fusible link that was the culprit. Per his message, the mechanic he took his jeep to---his was 97, mine 99, so comparable---said that this link also powers the auxiliary fan.

Light bulb! I have disconnected my aux fan since it stopped working a while ago. (Which happens to be issue # 2).

Per the article I was reading, the mechanic said if the aux fan fails it can overload this link, causing a variety of electrical issues. Anyone have an idea what he is referring to?

Also, I'm pretty sure the reason my fan failed was due to my A/C being completely empty--no pressure. Likely issue there is the evaporator. :doh:

So, here's my thought. My A/C system leaks out, fan fails causing this link to fail, causing the airbag light to make my blood pressure spike.

If I'm an idiot...don't be shy. Thanks!

Click to expand...

I'd have to call BS on that thread in that link. If the fusible link blows the alternator would be removed from the PDC bus and he would be operating on battery power only. It was probably a 40 Amp Maxi Fuse he changed in the PDC.

Here's a pic of the PDC showing the fusible link attachment at end of the PDC, on the the PDC bus (Green wire). The battery is sandwiched under the alternator (fusible link) connector.

OK. That makes sense. I actually pulled that link and cleaned the daylights out of it when I changed my alternator. At this point, I'm throwing anything out there to see what sticks. I did notice another thing concerning the airbag light. It doesn't seem to come on until the vehicle warms up. That makes me think more in terms of electronics then grounds or connections. That would make me think it's maybe a faulty or failing module. Is there a way to test that bugger or is this about the time I have to drop $100 to get the SRS system codes pulled from the stealership?

wolfman_023 said:

OK. That makes sense. I actually pulled that link and cleaned the daylights out of it when I changed my alternator. At this point, I'm throwing anything out there to see what sticks. I did notice another thing concerning the airbag light. It doesn't seem to come on until the vehicle warms up. That makes me think more in terms of electronics then grounds or connections. That would make me think it's maybe a faulty or failing module. Is there a way to test that bugger or is this about the time I have to drop $100 to get the SRS system codes pulled from the stealership?

Click to expand...

Use the $100 towards a replacement Air Bag Module. Try a junk yard.

I've found a few on Ebay from "reputable" sellers. (Take that term at face value..No China sellers for damn sure.) I guess I'll go that route then. I just hate throwing parts at stuff without knowing that it's the cause.

any independent shop worth a salt will have a scan tool capable of pulling air bag codes.

sometimes parts stores do too.

Hey Digger. Good to hear from ya. You saved me a ton of aggravation on my last venture into the electrical world.

I've checked all the local parts stores. They can pull CEL codes, but not SRS codes. I've got a few calls out to some local shops. 1st two I checked wanted $100 to run the diagnostic. Seems a bit steep just to pull the error log.

greedy fookers

I know right. Oh well, they don't call em J.E.E.P 's for nuthin!

I would expect that a CEL would come on for an ACM fault. Apparently you're not getting one. And if the ACM was faulty, it would probably corrupt the CCD Data Bus.

Could be a fault in the clockspring or wiring from the ACM to the clockspring (?).

im having same problem with airbag

No CEL. I just cleared that from another issue I was having. I've been driving for over a week now and the CEL hasn't come back. That being said, I didn't think the SRS system tripped the CEL since it is a self testing system.

I just replaced the clockspring and took at look at it's internals before installing it. All connections were solid and the "spring was in good condition. For the heck of it, I even ran continuity on it. All tested fine.

Also, from my earlier note, you can disregard the note about the car heating up. It happens at all times. Cold start, after it warms up, driving, idling. There's no apparent pattern to it. even the amount of time the light stays on or stays off is random. Could that still be some issue with the clockspring if it does it without me even touching the wheel?

Just an update on a few things I have looked at. I was playing around with the electric fan yesterday. I have no idea why these two things should have to do with one another, and maybe I'm just reading into this, but here goes.

I plugged my electric fan back into the connector, turned the jeep on and disconnected the temperature sensor on the thermostat housing. Fan did not come on. From what I've been reading, this indicates a bad fan or a bad fan relay correct?

Anyway, after that, I disconnect my battery to clear the CEL code that was thrown from me disconnecting the temp. sensor. I assume this cleared the SRS system errors too.

I reconnect the battery and take a half a dozen short trips....no airbag light, which is rare. Usually it comes on right away. It stayed off yesterday and all the way to work today until, I swear, the damn thing came on right when my t-stat opened...195*.

Please tell me that is just coincidence?

Coincidental unless there is an issue with the gauge cluster. Check the easy stuff first. Ground, and clean power to the unit. Fuses 26 and 27 in the junction block are for the ACM. LG/Yl is RUN. DB/YL is ST/RUN. The ground is either BK/YL or BK/PK depending on the option package of your XJ.

The fan failure has nothing to do with AC failure. Try unplugging the fan and seeing if you have voltage to it when you unplug the temp sensor. If you do the fan is toast. If not either the relay is bad or the fuse is blown. (Both of which can be caused by a fan drawing to much amperage.) On the fan plug the LB wire is your 12v. Don't forget to check the ground is good (A poor ground can cause the fan to draw excessive current.). The relay (bottom left hand full size relay) can be checked by just swapping it with another. I would (with the motor running and the temp sensor unplugged) swap it with the starter relay.