Flasher/Warnings CPU

[Casey]

It was great to see gt_james and his white FB on Saturday at the RetroRides event at Goodwood.

James brought me a couple of "CPUs" to test:

20220524_141837.jpg (123.81 KiB) Viewed 9706 times

James was happy for me to post up my findings on here.

The one on the right is 100% OK

The one on the left has minor problem in that the ignition barrel light timer isn't working. It should turn off after 25 seconds or so, after the door is opened and if the ignition isn't switched on. It stays on permanently, or until the ignition is switched on, so my never have been spotted. The intermittent wipe doesn't always work either, but wiggling the connector shows it is just a dodgy blade connection, not the circuit board. I'll take this one apart and see if I can locate a fix the faults so it's 100% operational.

[gt_james]

Was good to catch up!

That’s weird, the one you have tested 100% ok had an intermittent problem with the indicators not working, and was cured by swapping the CPU to a good one (on loan from Jesse )

[Casey]

It could be the main connector is a bit dodgy, I've found that is an issue with several of these units. I'll look again for an intermittent fault if I move the connector around.

[gt_james]

Hi Malc, have you looked any further into the intermittent fault?

I've had a thought about a possible mod/improvement. Do you think it would be feasible to add one of these 3 flash lane change timers to the indicator circuit, I must admit its a nice feature on modern cars for motorway driving!

https://www.carbuilder.com/uk/lane-chan ... sher-timer

If so... can I send one over to you whilst you have the CPU

[Casey]

Hi James. I've not had a chance to take a second look to confirm/fix an intermittent fault. I'll probably take another look later this coming week.

I've had a look at that "3 flashes" (piggy back) module and agree it would be a useful upgrade in functionality. On looking at how this module connects I can see two potential issues:

1. If this module is placed inside the "CPU" unit, it would require an extra wiring "loom" to tap in somewhere to the indicator "Right" and "Left" circuits (this could be at the cluster switch or another convenient point). I think the loom would only require 2 wires though, all other required connections can be picked up from within the "CPU" box internally.

2. The RX-7 flasher circuit is very dependent on the lamp load to operate correctly. It's not clear from the module wiring diagram if this piggy-back module provides it's own flasher function or acts as a timer/counter, utilising the existing car's flasher circuit. If the latter (which I suspect is the case), the load presented to the RX-7 flasher circuit may be such that the flasher circuit will not operate with the module as it's load, instead of its expected direct connection to the lamps. When I first tested the flasher circuit I could not get it to work when using a lower load. The high current flow to the lamps is critical to the circuit operation.

It would certainly require some bench testing to see if this module would function as intended when "piggy-backed" onto the RX-7 circuitry.

If you are happy for me to do some testing, but with no guarantee of a success outcome, feel free to send over one of those modules. If successful on the bench, I could modify your module and then you'd simply need to determine the best point to wire into the right and left indicator circuits.

[gt_james]

Cheers for the input Malcom, if you’re happy to try it I will order one and send it to you

[Casey]

Yep, if you'd like to send me a module James, I'll bench test it to and see if will work

[Casey]

It was great to see gt_james and his white FB on Saturday at the RetroRides event at Goodwood.

James brought me a couple of "CPUs" to test:

GT_James 2 CPU modules.jpg (123.81 KiB) Viewed 9649 times

James was happy for me to post up my findings on here.

The one on the right is 100% OK

The one on the left has minor problem in that the ignition barrel light timer isn't working. It should turn off after 25 seconds or so, after the door is opened and if the ignition isn't switched on. It stays on permanently, or until the ignition is switched on, so my never have been spotted. The intermittent wipe doesn't always work either, but wiggling the connector shows it is just a dodgy blade connection, not the circuit board. I'll take this one apart and see if I can locate a fix the faults so it's 100% operational.

I retested both these modules today and got identical results.

I tried wiggling the connectors on both units to check for any further issues and, apart from the dodgy intermittent wipe function on the module to the left (solved by wiggling), all the functions on the unit to the right were solid as a rock.

I'll look to clean the connector on the left module, and fix the barrel light delay malfunction. I can then use that unit as a test bed for the "lane change, 3 flashes" add-on module that James is going to send to me.

[Casey]

One of Jame's CPU's had a fault with the ignition barrel light timer, so I took that module apart today to do a visual check. The barrel light should
come on when the driver's door is opened, and go off when the ignition is turned on, or after ~30 seconds. The light was remaining lit, so the timer circuit had failed.

I immediately spotted the classic signs of a blown electrolytic capacitor; the top of the case had bulged slightly and there were clear signs electrolyte leakage. The 3 "score" marks on the capacitor are there to create a weak point if pressure builds up and allow the capacitor to bulge and leak, to prevent it exploding.

On checking my circuit diagram, this component is a critical part of the barrel light timer - bingo, hopefully an easy and cheap fix!

I also spotted some green verdigris on the connectors blades, which you can see in the photo, and would explain the intermittent operation I spotted. Those blades should clean up OK.

20220715_192224.jpg (112.72 KiB) Viewed 9611 times

[ian65]

I brought my ecu to Castle Combe last weekend to give to you for testings but forgot and left it in the car all weekend!