Assistance with TPMS Wiring Schematic?

Assistance with TPMS Wiring Schematic?

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Discussion

DB9VolanteDriver

Original Poster:

2,612 posts

175 months

Thursday 14th June 2012
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Can anyone identify the 4 wires for the Smart Tire TPMS, vintage late 2008 car build?

The 4 wires are: violet w/red tracer (or vice versa), red, white, and black.

For an earlier system on a DB9 (MY2004), the wires were red, white, black and green/white. The red and white wires were identified as the fault signals going to the dash fault-warning system, while the black and G/W were identified as ground and fused power, respectively.

I'm assuming (I know...) that violet/red is the power for the new black box, with the other 3 remaining the same. Anyone with a schematic out there they could refer to for a late(r) model?

Thanks.

MichaelV8V

650 posts

260 months

Thursday 14th June 2012
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DB9VolanteDriver

Original Poster:

2,612 posts

175 months

Friday 15th June 2012
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MichaelV8V said:
I have that one. Unfortunately it doesn't cover the later version of the Smart Tire system, hence the query.

BingoBob

1,098 posts

146 months

Friday 15th June 2012
quotequote all
I am inclined to agree with your assessment.

It's fairly safe to assume that black is the ground. You coudl test the violet / red with a multimeter to see if you get 12V with the ignition on and 0V with it off.

As for the communications wire, do you dare unplug them to see what they do?

BingoBob

1,098 posts

146 months

Friday 15th June 2012
quotequote all
Just a thought: could the power supply wires be a bigger wire gauge than the communications wires? That seems to be the case with the older system.

Can I ask what your problem is?

DB9VolanteDriver

Original Poster:

2,612 posts

175 months

Friday 15th June 2012
quotequote all
BingoBob said:
I am inclined to agree with your assessment.

It's fairly safe to assume that black is the ground. You coudl test the violet / red with a multimeter to see if you get 12V with the ignition on and 0V with it off.

As for the communications wire, do you dare unplug them to see what they do?

They are all unplugged (one connector) at the moment, resulting in two messages: one for TPMS system fault and the other for a low pressure warning, which is consistent with the schematic I have that indicates there are two 'signal' wires from the TPMS box.

I'm guessing that when the TPMS is powered and receiving valid sensor values that it actively grounds both of these signals to turn the messages off in the fault display on the instrument panel.

I guess I'll just check which wires are power and ground, and then short the 2 remaining signals to ground, which should turn off the messages. Since the brake pad warning signals are implemented with an open to turn on the dash light, I can't imagine that the TPMS outputs are arranged in the opposite state (but it would be good to know for sure...).

BingoBob

1,098 posts

146 months

Friday 15th June 2012
quotequote all
Isn't the smartire system a kind of add-on box? That would give weight to your idea of the outputs being switched rather than, say, CAN or other communication protocol which wouldn't be a good idea to ground.

DB9VolanteDriver

Original Poster:

2,612 posts

175 months

Friday 15th June 2012
quotequote all
BingoBob said:
Isn't the smartire system a kind of add-on box? That would give weight to your idea of the outputs being switched rather than, say, CAN or other communication protocol which wouldn't be a good idea to ground.
They are definitely On/Off, not serial links. I was just trying to figure out the state that turns them OFF. I'm guessing that the dash module electronics pulls them high when open, so grounding them to deactivate the message.

BingoBob

1,098 posts

146 months

Saturday 16th June 2012
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Interesting stuff. If you are right then that leaves the door open for fitting an aftermarket system when the sensors start to fail. It looks like Bendix isn't really offering the smartire system for cars anymore so parts may become rare / expensive once their contractual obligation to supply AM is up.

BingoBob

1,098 posts

146 months

Thursday 21st June 2012
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Did you make any progress with this?

DB9VolanteDriver

Original Poster:

2,612 posts

175 months

Thursday 21st June 2012
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No, I haven't. But I will soon, I hope, and will post the results.

jamesc12

280 posts

202 months

Thursday 21st June 2012
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DB9VolanteDriver said:
No, I haven't. But I will soon, I hope, and will post the results.
Watching out these results. Cheers.

DB9VolanteDriver

Original Poster:

2,612 posts

175 months

Thursday 5th July 2012
quotequote all
So here's the deal to extinguish the dash messages:

1) Disconnect the TPMS at the connector block under the dash (white connector).

2) Identify the 4 wires on the car-side of the harness: these should be red, white, black and blue/red.
Blue/red is 12V switched power
Black is ground
Red is the TPMS system fault line
White is the tyre low pressure fault line

3) At the car-side connector half, short the black, red and white pins together, using whatever technique you are comfortable with. This will tell the dash warning system that everything is OK with the TPMS and that none of the tyres are underpressure.

Myself, I just cut the mating connector pigtail off the back of the TPMS module (in the middle of its length), cut the sheath back, and then twisted together the Orange, Brown and Black wires, leaving the Red power wire untouched. Since I don't particularly like soldering because of the chance of getting a cold solder joint, I just used a small wire nut to twist the 3 wires together. If I ever want to use the TPMS system again, I can undo the nut and splice the connector back on to the TPMS pigtail. Then I just plugged the connector back into the one on the car, and voila, no more dash warnings.

Just for clarity, the Orange wire on the TPMS side corresponds to the Red wire on the car-side of the connector. Brown corresponds to White, Black to Black, and Red to the Blue/Red, respectively.

If this isn't clear, let me know.

BingoBob

1,098 posts

146 months

Thursday 5th July 2012
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Very good information. Thanks for that!

BingoBob

1,098 posts

146 months

Thursday 5th July 2012
quotequote all
Just a thought:

Since there is no CAN message coming out of the smartire system, why not replace it with an aftermarket kit at a fraction of the price? It would need to have an output to connect it to the car, though;

smartmove

156 posts

211 months

Tuesday 10th September 2013
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Just did this as tyre changing people broke a sensor when changing front tyres (even though they said it was already broken). Worked a treat. Thanks!

Manwhoneverwas

598 posts

130 months

Sunday 27th October 2013
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Thanks to DB9VolanteDriver for this excellent piece of information.
Since I am fitting newer style Vantage S alloys which have the modern AM TPMS system (not compatible with my older system) this information enabled me to disable the TPMS system without any dash warning lights.
I had actually bought 4 TPMS sensors to eventually replace my existing ones when the batteries fail, but these will now be sold off on Ebay

baldyash

98 posts

136 months

Saturday 29th November 2014
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Resurrection time-- Shorted the white plug as per temporarily & success. Redid it properly & the dash warning is still lite.Redid with smartire dis & connected no different. Re-soldered the other side of the plug, as per, with box dis. & conn. & still the light remains with 2 codes ---tyre & system fault. Do you think I need a proper(AM) reset to the system? Its very frustrating as I thought I'd solved it!!!

Had a sensor fail & my local tyre dealer thought they had a generic replacement but were unable to source eventually & I object to AM price & also I believe you have to get a system reset from AM madranting

DB9VolanteDriver

Original Poster:

2,612 posts

175 months

Saturday 29th November 2014
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Would like to assist, but honestly, your description is too cryptic for me to understand the issue. If you can elaborate, then maybe we can help.

baldyash

98 posts

136 months

Sunday 30th November 2014
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I sensor failed. I unplugged the smartire box. Shorted the 3 wires in the white plug & the dash display disappeared.I then removed my temporary wire & soldered the 3 wires together behind the plug-(car side) ---plugged the smartire in & dash display was there again.I unplugged the smartire box ( so shorts were still there but white plug not now connected to smartire)---dash display still there.Did try a couple of other combos but dash display still there. I will get a separate earth next & check that next shorting to the 2 sensor o/p wires