Toothed belt service warning
03-11-2008, 10:59 AM
#16
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Reading through this thread, I am left wondering what could cause a "toothed belt service" light on my '90 GT that is not in the area of the timing belt covers, etc.
I just had the timing belt changed including:
1. timing belt
2. water pump
3. rebuilding tensioner with new bushings, boot and cap
The "toothed belt service" light has come on many times since, both during and after warm-up. I (don't ignore it) can reset it via the control stalk.
Since it is not constantly on, I don't see that I can perform the continuity check mentioned above. Is there a way I can confirm the problem is NOT related to the tensioner, spade connector or actual belt looseness? In other words how can I confirm the problem is not in the instrument panel, etc.?
Thanks for you thoughts in advance
I just had the timing belt changed including:
1. timing belt
2. water pump
3. rebuilding tensioner with new bushings, boot and cap
The "toothed belt service" light has come on many times since, both during and after warm-up. I (don't ignore it) can reset it via the control stalk.
Since it is not constantly on, I don't see that I can perform the continuity check mentioned above. Is there a way I can confirm the problem is NOT related to the tensioner, spade connector or actual belt looseness? In other words how can I confirm the problem is not in the instrument panel, etc.?
Thanks for you thoughts in advance
Next step is to check the belt tension and the tensioner system itself.
Hope this helps a bit.
03-11-2008, 12:07 PM
#17
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I have seen several engines where the tensioner warning wire was simply grounded to the engine to defeat the warning system...I speculate that a "mechanic" simply got tired of comebacks and "fixed it".....after all it was not his car ! The warning system is not very reliable but as mentioned needs to be looked at when it thinks something may be wrong... You should contact the shop and see IF they have a tension tool many just do it by feel !
03-11-2008, 12:23 PM
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I agree, just don't know if it is the belt or the warning system right now.
This is a great plan, thanks. I will try this today. At least it will give some comfort that the warning system is working properly.
I didn't ask, but would be very surprised if the shop does not have a tension tool.
One thing you can try is to disconnect the connector that goes into the center TB cover just behind the dipstick. Then take a length of wire and attach it to ground. Run the engine. After about 3 min (no less), check the car's display for the belt warning. You should not have a warning. With the engine still running, you should be able to disconnect this jumper from ground and it will trigger the belt warning immediately. If it does, then your TB warning system is functioning properly.
Next step is to check the belt tension and the tensioner system itself.
Hope this helps a bit.
Next step is to check the belt tension and the tensioner system itself.
Hope this helps a bit.
I have seen several engines where the tensioner warning wire was simply grounded to the engine to defeat the warning system...I speculate that a "mechanic" simply got tired of comebacks and "fixed it".....after all it was not his car ! The warning system is not very reliable but as mentioned needs to be looked at when it thinks something may be wrong... You should contact the shop and see IF they have a tension tool many just do it by feel !
03-11-2008, 02:38 PM
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One thing you can try is to disconnect the connector that goes into the center TB cover just behind the dipstick. Then take a length of wire and attach it to ground. Run the engine. After about 3 min (no less), check the car's display for the belt warning. You should not have a warning. With the engine still running, you should be able to disconnect this jumper from ground and it will trigger the belt warning immediately. If it does, then your TB warning system is functioning properly.
Next step is to check the belt tension and the tensioner system itself.
Hope this helps a bit.
Next step is to check the belt tension and the tensioner system itself.
Hope this helps a bit.
Perhaps I found the problem though, as when I pulled the tensioner lead, the end fell off. Making me think it was not providing a consistent connection as perhaps it was fractured...? Photo below (sorry about the focus).
The question now is how to repair this to determine whether it was the cause?
03-11-2008, 03:08 PM
#20
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Well Stan, that's why I suggested you test it. If it still gave you a warning, there's a problem. Not sure how you fix it. I'll bet you can get a replacement connector from one of the suppliers and re-wire it in.
03-11-2008, 07:07 PM
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Found I still had an 86 harness, the part looks the same, so I am hoping it will work out. Have to wait at this point, as I sent the computers out to be checked to confirm the LH is not the cause of the surge problem.
03-11-2008, 10:28 PM
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03-11-2008, 10:57 PM
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Stan,
I suggest you also check the condition of the contact bridge. I found broken contact bridges due to fatigue in the last two TB/WP I did.
In one case, the belt was tensioned properly and the broken contact strip triggered the warning light (or so I think).
In the second case (on a recently acquired '86.5) the TB warning light would come on after three minutes. When I did the TB/WP job, I found the TB belt tension was 3.0 on the 9201 tool and the contact bridge was in two pieces.
It appears the flat semi-rigid copper bridge is not that durable over time. Is there a contact bridge made of braided copper strands that is a little more flexible?
Adam
I suggest you also check the condition of the contact bridge. I found broken contact bridges due to fatigue in the last two TB/WP I did.
In one case, the belt was tensioned properly and the broken contact strip triggered the warning light (or so I think).
In the second case (on a recently acquired '86.5) the TB warning light would come on after three minutes. When I did the TB/WP job, I found the TB belt tension was 3.0 on the 9201 tool and the contact bridge was in two pieces.
It appears the flat semi-rigid copper bridge is not that durable over time. Is there a contact bridge made of braided copper strands that is a little more flexible?
Adam
03-11-2008, 11:18 PM
#24
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Yes, this was changed to a braided wire in 89. All the 928 vendors usually recommend you by that instead of the rigid copper piece.
03-12-2008, 12:36 AM
#25
There is a Technical Bulletin regarding the TB alarm circuit and how to test it, which is quite useful.
Unfortunately I not at home and cannot give you a reference number, however, it is included in JM Technical CDs.
I used this Bulletin to confirm the alarm operation last month. From memory the alarm circuit in Digital Dash Car is a closed loop and when the circuit is opened it alarms.
Tails 1990 928S4 Auto
Unfortunately I not at home and cannot give you a reference number, however, it is included in JM Technical CDs.
I used this Bulletin to confirm the alarm operation last month. From memory the alarm circuit in Digital Dash Car is a closed loop and when the circuit is opened it alarms.
Tails 1990 928S4 Auto
03-12-2008, 10:18 AM
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There is a Technical Bulletin regarding the TB alarm circuit and how to test it, which is quite useful.
Unfortunately I not at home and cannot give you a reference number, however, it is included in JM Technical CDs.
I used this Bulletin to confirm the alarm operation last month. From memory the alarm circuit in Digital Dash Car is a closed loop and when the circuit is opened it alarms.
Tails 1990 928S4 Auto
Unfortunately I not at home and cannot give you a reference number, however, it is included in JM Technical CDs.
I used this Bulletin to confirm the alarm operation last month. From memory the alarm circuit in Digital Dash Car is a closed loop and when the circuit is opened it alarms.
Tails 1990 928S4 Auto
03-13-2008, 01:10 PM
#29
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I did receive the solid one from a vendor here in winter 2002-3. It promptly broke and I had to tear it down again. Ask for the braided and don't accept the solid one.
03-13-2008, 08:08 PM
#30
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If anyone is stuck in future, not having added this part to the vendors order, it is a quick DIY job to fabricate one - 5 min. with a crimping tool and some copper braid.