TB and ABS questions
#1
02-10-2017, 08:35 PM
TB and ABS questions
Newbie here. Greetings to all.
I have three questions. 1. The 1998 Xj8 Throttle Body is known to have internal issues. Mine idles at 900rpm+, would not drop to the normal 750rpm range, and would sometimes even surge upon deceleration. I've cleaned the gunk in the flap bore, but to minimal effect. Now it seems the TB itself would produce a rather loud humming noise when cold, and produce yet another kind of higher-pitched noise when close to full throttle. Do these signs confirm replacing the TB imminent? 2. What does the unit by the ABS Module that says "passive sound" do? Any harm disconnecting it? 3. My ABS+Stability Control Fail light started showing, rather permanently. Factory OBDII reads ABS Module at fault. I still decided to clean the wheel speed sensors myself first. Did that, hard reset the car (but did not disconnect the Module and motor wires), no effect. Drove a few dozen miles, decided it was probably the module after all, so I attempted to remove the module and have it fixed (battery negative and module+motor wires off). I was interrupted and had to stop the removal and drive off with the car, so I reconnected the battery, but not the ABS wires. Car runs, but dash shows "incorrect part fitted." So I stopped the car, re-connected the ABS wires, and there! the ABS+ASC warning light went away!! It has been until now another few dozen miles without the warning lights returning! What has happened?
Paul
I have three questions. 1. The 1998 Xj8 Throttle Body is known to have internal issues. Mine idles at 900rpm+, would not drop to the normal 750rpm range, and would sometimes even surge upon deceleration. I've cleaned the gunk in the flap bore, but to minimal effect. Now it seems the TB itself would produce a rather loud humming noise when cold, and produce yet another kind of higher-pitched noise when close to full throttle. Do these signs confirm replacing the TB imminent? 2. What does the unit by the ABS Module that says "passive sound" do? Any harm disconnecting it? 3. My ABS+Stability Control Fail light started showing, rather permanently. Factory OBDII reads ABS Module at fault. I still decided to clean the wheel speed sensors myself first. Did that, hard reset the car (but did not disconnect the Module and motor wires), no effect. Drove a few dozen miles, decided it was probably the module after all, so I attempted to remove the module and have it fixed (battery negative and module+motor wires off). I was interrupted and had to stop the removal and drive off with the car, so I reconnected the battery, but not the ABS wires. Car runs, but dash shows "incorrect part fitted." So I stopped the car, re-connected the ABS wires, and there! the ABS+ASC warning light went away!! It has been until now another few dozen miles without the warning lights returning! What has happened?
Paul
#2
02-11-2017, 07:24 AM
Veteran Member
#3
02-12-2017, 03:45 AM
#4
02-12-2017, 05:04 AM
#5
02-12-2017, 06:55 AM
Veteran Member
1. TB: Does your Cruise Control work? Is an indication for a possible vacuum leak, but there are unfortunately other causes as well.
2. Passive Sound: I will need to go down and check what you are talking about
.
3. If the problem is the soldered contacts, you will experience a come'and-go scenario for a while, gradually getting worse. Perhaps your wiggling resulted in some better contact, but it will come back.
Did you check your battery? Lower battery voltages can play havoc with fault messages as well.
4. Trim levels: I can set you up with some measuring and explanation.
Eric
2. Passive Sound: I will need to go down and check what you are talking about
.3. If the problem is the soldered contacts, you will experience a come'and-go scenario for a while, gradually getting worse. Perhaps your wiggling resulted in some better contact, but it will come back.
Did you check your battery? Lower battery voltages can play havoc with fault messages as well.
4. Trim levels: I can set you up with some measuring and explanation.
Eric
#6
02-12-2017, 07:36 AM
3. Is quite possibly the bad solder joints Eric mentioned. It's not terribly difficult...basically remove the module from the ABS pump, open the cover (with a hack saw), look closely under strong light at the solder joints, resolder the affected joints....and those around it, refit cover (with epoxy), reinstall module, hard reset and you should be good.
Do a search on this and you'll find step by step instructions, with pictures. It really is pretty simple....
Do a search on this and you'll find step by step instructions, with pictures. It really is pretty simple....