Check Engine Light, ABS light, Tachometer off by 1000 rpm=I need some help

Simultaneous, pan-vehicle electrical system pathologies in seemingly unrelated systems generally suggests the lowest common denominator they all have in common: the supply and charging system.

You may have a loose battery or ground connection or a battery with issues. You may have a rectifier or regulator issue in the alternator.

Have you recently done any under-hood work to the car? Any arc-welding (MIG, TIG etc)?

The recent work is an important detail to mention.

Is the Tach off by 1k, or is it stuck at a certain point? IE, if the motor is reved does the tach respond?

Note, the tach is driven by a signal from the PCM. Possible this could be a ground issue to the cluster. Note, the cluster, GEM, radio share the same ground located on the left side of the center console.

During the recent install, was any work done behind the dash? Esp right of the radio/center console area?

The air injection system is a different issues entirely. I spent some time looking over the service manual. My 96 reference is just not as "user friendly" as the 2002-03 manual. This makes it harder to "gleam" information. In addition, the format will not allow me to cut/paste into an online post.

If I had to make a guess on what is wrong, the solid state relay of the air injection system is bad. However, there is an entire series of tests to trouble shoot the entire system. It's fairly lengthy.

Another common problem with the V6 air injection system is exhaust rot/rust through because the AC water drips upon the exhaust. .

>>from 96 service CD.

HM18 CHECK FOR VOLTAGE AT SOLID STATE RELAY

DTC P1413 indicates EAIR monitor circuit is low while the EAP was commanded ON.

l Key off.
l Disconnect Solid State Relay.
l Key on.
l Measure voltage between B+ circuit at Solid State Relay vehicle harness connector and chassis ground.
l Is voltage greater than 10.5 volts?

Yes
GO to «HM19».

No
GO to «HM24».

HM19 CHECK EAIR MONITOR CIRCUIT FOR VOLTAGE

l Key off.
l Reconnect Solid State Relay.
l Disconnect EAP.
l Measure voltage between EAIR monitor circuit at the EAP vehicle harness connector and chassis ground.
l Key on.
l Is voltage greater than 10.5 volts?

Yes
IF DTC P0411 is present, REPLACE EAP. If not, GO to «HM23».

No
GO to «HM20».

HM20 CHECK EAIR MONITOR CIRCUIT FOR VOLTAGE, SSR CONNECTED

l Key off.
l SSR connected.
l EAP disconnected. Disconnect PCM, install breakout box.
l Measure voltage between Test Pin 5 and chassis ground.
l Key on.
l Is voltage greater than 10.5 volts?

Yes
REPLACE PCM. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

No
GO to «HM21».

HM21 CHECK CONTINUITY OF EAIR MONITOR CIRCUIT

l Key off.
l Disconnect Solid State Relay.
l Disconnect PCM. Install breakout box.
l EAP disconnected.
l Measure resistance between Test Pin 5 at the breakout box and EAIR monitor circuit at the Solid State Relay vehicle harness connector.
l Measure resistance between EAIR monitor circuit at the Solid State Relay vehicle harness connector and EAIR monitor circuit at the EAP vehicle harness connector.
l Is each resistance less than 5.0 ohms?

Yes
GO to «HM22».

No
SERVICE open EAIR monitor circuit. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM22 CHECK EAIR MONITOR CIRCUIT FOR SHORT TO GROUND

l Key off.
l Solid State Relay disconnected.
l EAP disconnected.
l Breakout box installed, PCM disconnected.
l Measure resistance between Test Pin 5 and Test Pin 51, 76 and 91 at the breakout box.
l Is each resistance greater than 10,000 ohms?

Yes
REPLACE Solid State Relay. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

No
SERVICE EAIR monitor circuit for short to ground. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM23 CHECK EAIR MONITOR CIRCUIT FOR VOLTAGE, EAP CONNECTED

l Key off.
l Reconnect EAP.
l Install breakout box. PCM connected.
l Key on, engine running.
l Measure voltage between Test Pin 5 at the breakout box and chassis ground.
l Is voltage greater than 10.5 after the 5 second delay?

Yes
REPLACE PCM. REMOVE breakout box. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

No
SERVICE open EAIR monitor circuit. REMOVE breakout box. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

HM24 CHECK CONTINUITY OF B+ CIRCUIT

l Key off.
l Solid State Relay disconnected.
l Measure resistance between Solid State Relay vehicle harness connector B+ circuit and Solid State Relay dedicated fuse B+ circuit.
l Is resistance less than 5 ohms?

Yes
SERVICE Solid State Relay dedicated fuse. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

No
SERVICE open B+ circuit. RECONNECT all components. COMPLETE PCM Reset to clear DTCs (REFER to Section 2A, «Powertrain Control Module (PCM) Reset»). RERUN «Quick Test».

<<<<Got tired cutting/pasting. Must stop>>>

just_a_guy84 said:

On my 1998 Mustang Cobra:

As the title states, this morning I started my car and the abs light stayed on, the Tach read about 2000 RPMS even though it was clearly idling. My right turn signal bulb was also illuminated and when I activated the signal it acted light I had a bulb burnt out. About halfway to work the abs light went off, the tach started reading normal and the signal began working again.

On the way home from work It did it again intermittently followed by the check engine light coming on. I pulled the engine codes at the auto parts store and came up with P1414: Secondary Air Injection Montitor Circuit High Input. I have no idea what or where that is. I would really appreciate any input. Otherwise the car runs like normal. I'm stumped.

Thanks you.

Click to expand...

Wow - I am experiencing the same issue, although it is now 5 years later than your encounter. So, what was the outcome - did you fix it? What was it?! HELP!